diff --git a/action.php b/action.php
index 64bca1d..e34f1b1 100644
--- a/action.php
+++ b/action.php
@@ -33,115 +33,178 @@ function returnToSender($msg, $arg = "") {
 switch ($VARS['action']) {
     case "finish_transaction":
         header("Content-Type: application/json");
-        $items = $VARS['items'];
-        $payments = $VARS['payments'];
-        $customer = $VARS['customer'];
-        $register = $VARS['register'];
-        $discountpercent = $VARS['discountpercent'];
-
-        if ($customer != "" && !$database->has('customers', ['customerid' => $customer])) {
-            exit(json_encode(["status" => "ERROR", "message" => lang("invalid customer", false)]));
-            // exit(json_encode(["status" => "ERROR", "message" => lang("", false)]));
-        }
-        if ($register != "" && !$database->has('registers', ['registerid' => $register])) {
-            exit(json_encode(["status" => "ERROR", "message" => lang("invalid register", false)]));
-        }
-        if ($register != "" && !$database->has('cash_drawer', ['AND' => ['registerid' => $register, 'close' => null]])) {
-            exit(json_encode(["status" => "ERROR", "message" => lang("cash not open", false)]));
-        }
-
-        $totalcharge = 0.00;
-        $totalpaid = 0.00;
-        $change = 0.0;
-        foreach ($items as $i) {
-            $totalcharge += $i['each'] * $i['qty'];
-            if (!$binstack->has('items', ['itemid' => $i['id']])) {
-                exit(json_encode(["status" => "ERROR", "message" => lang("invalid item", false)]));
+        $error = null;
+        $oktx = null;
+        $database->action(function ($database) {
+            global $VARS, $binstack, $error, $oktx;
+
+            $items = $VARS['items'];
+            $payments = $VARS['payments'];
+            $customer = $VARS['customer'];
+            $register = $VARS['register'];
+            $discountpercent = $VARS['discountpercent'];
+            $cashid = null;
+            $editing = false;
+
+            if (isset($VARS['txid']) && $database->has('transactions', ['txid' => $VARS['txid']])) {
+                $editing = true;
+                $txid = $VARS['txid'];
+                $cashid = $database->get('transactions', 'cashid', ['txid' => $txid]);
+                if (!$database->has('cash_drawer', ['AND' => ['cashid' => $cashid, 'close' => null]])) {
+                    $error = lang("cash already closed", false);
+                    return false;
+                }
+                // Nuke the payments to make room for their replacements
+                // Delete payments
+                $oldpayments = $database->select('payments', ['payid', 'amount', 'type', 'certid'], ['txid' => $txid]);
+                foreach ($oldpayments as $p) {
+                    // Reset gift card balances
+                    if (!is_null($p['certid'])) {
+                        $database->update('certificates', ['amount[+]' => $p['amount']], ['certid' => $p['certid']]);
+                    }
+                    $database->delete('payments', ['payid' => $p['payid']]);
+                }
             }
-        }
-        foreach ($payments as $p) {
-            if (!$database->has('payment_types', ['typename' => $p['type']])) {
-                exit(json_encode(["status" => "ERROR", "message" => lang("invalid payment type", false)]));
+
+            if ($customer != "" && !$database->has('customers', ['customerid' => $customer])) {
+                $error = lang("invalid customer", false);
+                return false;
             }
-            $totalpaid += $p['amount'];
-            if ($p['type'] == "giftcard") {
-                if (!$database->has('certificates', ['AND' => ['amount[>=]' => $p['amount'], 'deleted[!]' => 1, 'certcode' => $p['code']]])) {
-                    exit(json_encode(["status" => "ERROR", "message" => lang("invalid giftcard", false)]));
+            if ($register != "" && !$database->has('registers', ['registerid' => $register])) {
+                $error = lang("invalid register", false);
+                return false;
+            }
+            if ($register != "" && !$database->has('cash_drawer', ['AND' => ['registerid' => $register, 'close' => null]])) {
+                $error = lang("cash not open", false);
+                return false;
+            }
+
+            if ($register != "" && $editing === false) {
+                $cashid = $database->get('cash_drawer', 'cashid', ['AND' => ['registerid' => $register, 'close' => null]]);
+            }
+
+            $totalcharge = 0.00;
+            $totalpaid = 0.00;
+            $change = 0.0;
+            foreach ($items as $i) {
+                $totalcharge += $i['each'] * $i['qty'];
+                if (!$binstack->has('items', ['itemid' => $i['id']])) {
+                    $error = lang("invalid item", false);
+                    return false;
+                }
+            }
+            foreach ($payments as $p) {
+                if (!$database->has('payment_types', ['typename' => $p['type']])) {
+                    $error = lang("invalid payment type", false);
+                    return false;
+                }
+                $totalpaid += $p['amount'];
+                if ($p['type'] == "giftcard") {
+                    if (!$database->has('certificates', ['AND' => ['amount[>=]' => $p['amount'], 'deleted[!]' => 1, 'certcode' => $p['code']]])) {
+                        $error = lang("invalid giftcard", false);
+                        return false;
+                    }
                 }
             }
-        }
 
-        if (is_numeric($discountpercent) && $discountpercent > 0 && $discountpercent < 100) {
-            $discountpercent = $discountpercent * 1.0;
-            $totalcharge *= 1.0 - ($discountpercent / 100.0);
-        } else {
-            $discountpercent = 0.0;
-        }
+            if (is_numeric($discountpercent) && $discountpercent > 0 && $discountpercent < 100) {
+                $discountpercent = $discountpercent * 1.0;
+                $totalcharge *= 1.0 - ($discountpercent / 100.0);
+            } else {
+                $discountpercent = 0.0;
+            }
 
-        if ($totalcharge > $totalpaid) {
-            exit(json_encode(["status" => "ERROR", "message" => lang("insufficient payment", false)]));
-        }
+            if ($totalcharge > $totalpaid) {
+                $error = lang("insufficient payment", false);
+                return false;
+            }
 
-        $cashid = null;
-        if ($register != "") {
-            $cashid = $database->get('cash_drawer', 'cashid', ['AND' => ['registerid' => $register, 'close' => null]]);
-        }
 
-        $database->insert('transactions', [
-            'txdate' => date('Y-m-d H:i:s'),
-            'customerid' => ($customer != "" ? $customer : null),
-            'type' => 1,
-            'cashier' => $_SESSION['uid'],
-            'cashid' => $cashid,
-            'discountpercent' => $discountpercent
-        ]);
-        $txid = $database->id();
-
-        foreach ($items as $i) {
-            $item = $binstack->get('items', ['name', 'qty'], ['itemid' => $i['id']]);
-
-            $database->insert('lines', [
-                'txid' => $txid,
-                'amount' => $i['each'],
-                'name' => $item['name'],
-                'itemid' => $i['id'],
-                'qty' => $i['qty']
-            ]);
-            $binstack->update('items', [
-                'qty[-]' => $i['qty']
-                    ], [
-                'itemid' => $i['id']
-            ]);
-        }
-
-        foreach ($payments as $p) {
-            $certid = null;
-            if ($p['type'] == "giftcard") {
-                $certid = $database->get('certificates', 'certid', ['certcode' => $p['code']]);
+            if ($editing === true) {
+                $database->update('transactions', [
+                    'txdate' => date('Y-m-d H:i:s'),
+                    'customerid' => ($customer != "" ? $customer : null),
+                    'type' => 1,
+                    'cashier' => $_SESSION['uid'],
+                    'cashid' => $cashid,
+                    'discountpercent' => $discountpercent
+                        ], [
+                    'txid' => $txid
+                ]);
+            } else {
+                $database->insert('transactions', [
+                    'txdate' => date('Y-m-d H:i:s'),
+                    'customerid' => ($customer != "" ? $customer : null),
+                    'type' => 1,
+                    'cashier' => $_SESSION['uid'],
+                    'cashid' => $cashid,
+                    'discountpercent' => $discountpercent
+                ]);
+                $txid = $database->id();
             }
-            $type = $database->get('payment_types', 'typeid', ['typename' => $p['type']]);
-            $database->insert('payments', [
-                'amount' => $p['amount'],
-                'data' => '',
-                'type' => $type,
-                'txid' => $txid,
-                'certid' => $certid
-            ]);
-        }
 
-        if ($totalcharge < $totalpaid) {
-            $change = $totalpaid - $totalcharge;
-            $database->insert('payments', [
-                'amount' => $change * -1.0,
-                'data' => '',
-                'type' => 1,
-                'txid' => $txid,
-                'certid' => null
-            ]);
-        }
+            $olditems = $database->select('lines', ['itemid (id)', 'qty', 'lineid'], ['txid' => $txid]);
+            foreach ($items as $i) {
+                $item = $binstack->get('items', ['name', 'qty'], ['itemid' => $i['id']]);
+
+                $database->insert('lines', [
+                    'txid' => $txid,
+                    'amount' => $i['each'],
+                    'name' => $item['name'],
+                    'itemid' => $i['id'],
+                    'qty' => $i['qty']
+                ]);
+                $binstack->update('items', [
+                    'qty[-]' => $i['qty']
+                        ], [
+                    'itemid' => $i['id']
+                ]);
+            }
 
-        exit(json_encode(["status" => "OK", "txid" => $txid]));
+            foreach ($payments as $p) {
+                $certid = null;
+                if ($p['type'] == "giftcard") {
+                    $certid = $database->get('certificates', 'certid', ['certcode' => $p['code']]);
+                }
+                $type = $database->get('payment_types', 'typeid', ['typename' => $p['type']]);
+                $database->insert('payments', [
+                    'amount' => $p['amount'],
+                    'data' => '',
+                    'type' => $type,
+                    'txid' => $txid,
+                    'certid' => $certid
+                ]);
+            }
 
+            if ($totalcharge < $totalpaid) {
+                $change = $totalpaid - $totalcharge;
+                $database->insert('payments', [
+                    'amount' => $change * -1.0,
+                    'data' => '',
+                    'type' => 1,
+                    'txid' => $txid,
+                    'certid' => null
+                ]);
+            }
+
+            foreach ($olditems as $i) {
+                $database->delete('lines', ['lineid' => $i['lineid']]);
+                $binstack->update('items', [
+                    'qty[+]' => $i['qty']
+                        ], [
+                    'itemid' => $i['id']
+                ]);
+            }
+
+            $oktx = $txid;
+            return true;
+        });
+
+        if (!is_null($error)) {
+            exit(json_encode(["status" => "ERROR", "message" => $error]));
+        } else {
+            exit(json_encode(["status" => "OK", "txid" => $oktx]));
+        }
         break;
     case "getreceipt":
         require_once __DIR__ . "/lib/generatereceipt.php";
diff --git a/lang/en_us.php b/lang/en_us.php
index 18b6ed9..76db4ac 100644
--- a/lang/en_us.php
+++ b/lang/en_us.php
@@ -118,4 +118,6 @@ define("STRINGS", [
     "x report" => "X Report",
     "z report" => "Z Report",
     "pick cash" => "Choose",
+    "cash already closed" => "Cash already closed, cannot edit this transaction.  Process a return instead.",
+    "update" => "Update",
 ]);
diff --git a/pages/pos.php b/pages/pos.php
index c40d631..9174b35 100644
--- a/pages/pos.php
+++ b/pages/pos.php
@@ -19,6 +19,16 @@ if (isset($_GET['switch']) || !isset($_SESSION['register']) || !$registeropen) {
 } else {
     $register = $database->get('registers', ['registerid (id)', 'registername (name)'], ['registerid' => $_SESSION['register']]);
     $showgridbydefault = $binstack->count('items', ['AND' => ['price[!]' => null, 'price[!]' => 0]]) <= GRID_BY_DEFAULT_MAX_ITEMS;
+    $items = [];
+    $payments = [];
+    $editing = false;
+    if (isset($VARS['txid']) && $database->has('transactions', ['txid' => $VARS['txid']])) {
+        $editing = true;
+        $items = $database->select('lines', ['lineid', 'amount', 'name', 'itemid', 'qty'], ['txid' => $VARS['txid']]);
+        $payments = $database->select('payments', ['[>]certificates' => 'certid', '[>]payment_types' => ['type' => 'typeid']], ['payments.amount', 'typename', 'icon', 'text', 'certcode'], ['txid' => $VARS['txid']]);
+        $tx = $database->get('transactions', ['[>]customers' => 'customerid'], ['txid', 'discountpercent', 'transactions.customerid', 'customers.name (customername)'], ['txid' => $VARS['txid']]);
+        echo "<input type=\"hidden\" id=\"txid\" value=\"$VARS[txid]\">";
+    }
     ?>
     <div class="modal fade" tabindex="-1" role="dialog" id="receiptmodal">
         <div class="modal-dialog" role="document">
@@ -122,7 +132,44 @@ if (isset($_GET['switch']) || !isset($_SESSION['register']) || !$registeropen) {
                 </div>
                 <div>
                     <div class="list-group list-group-flush" id="pos-lines-box">
-                        <!-- Items go here -->
+                        <?php
+                        foreach ($items as $i) {
+                            ?>
+                            <div class="list-group-item" data-itemid="<?php echo $i['itemid']; ?>">
+                                <div class="d-flex w-100 justify-content-between mb-2">
+                                    <h5 class="item-name"><?php echo $i['name']; ?></h5>
+                                    <h5>
+                                        <span class="badge badge-light">
+                                            $<span class="line-total"><?php echo number_format($i['amount'] * $i['qty'], 2); ?></span>
+                                        </span>
+                                    </h5>
+                                </div>
+                                <div class="d-inline-flex">
+                                    <div class="input-group qty-control">
+                                        <div class="input-group-prepend">
+                                            <span class="input-group-text pr-1"><b>$</b></span>
+                                        </div>
+                                        <input type="money" class="form-control item-price" value="<?php echo number_format($i['amount'], 2); ?>"/>
+                                        <div class="input-group-prepend">
+                                            <span class="input-group-text px-2"><i class="fas fa-times"></i></span>
+                                            <button class="btn btn-red qty-minus" type="button"><i class="fas <?php
+                                                if ($i['qty'] > 1) {
+                                                    echo "fa-minus";
+                                                } else {
+                                                    echo "fa-trash";
+                                                }
+                                                ?>"></i></button>
+                                        </div>
+                                        <input type="number" class="form-control item-qty px-2" value="<?php echo $i['qty']; ?>" />
+                                        <div class="input-group-append">
+                                            <button class="btn btn-light-green qty-plus" type="button"><i class="fas fa-plus"></i></button>
+                                        </div>
+                                    </div>
+                                </div>
+                            </div>
+                            <?php
+                        }
+                        ?>
                     </div>
                 </div>
             </div>
@@ -138,11 +185,25 @@ if (isset($_GET['switch']) || !isset($_SESSION['register']) || !$registeropen) {
                 <div class="card-body d-flex justify-content-center flex-wrap py-0 my-0">
                     <div class="btn m-1" id="addcustomerbtn">
                         <i class="fas fa-user-circle"></i>
-                        <span id="customerbtnlabel"></span>
+                        <span id="customerbtnlabel"><?php
+                            if ($editing && isset($tx['customername'])) {
+                                echo $tx['customername'];
+                            }
+                            ?></span>
                         <span class="sr-only"><?php lang("customer"); ?></span>
                     </div>
-                    <div class="btn m-1" id="discountpercentbtn" data-percent="0">
-                        <span id="discountpercentbtnlabel"></span>
+                    <div class="btn m-1" id="discountpercentbtn" data-percent="<?php
+                    if ($editing && isset($tx['discountpercent']) && $tx['discountpercent'] != 0) {
+                        echo (float) $tx['discountpercent'];
+                    } else {
+                        echo "0";
+                    }
+                    ?>">
+                        <span id="discountpercentbtnlabel"><?php
+                            if ($editing && isset($tx['discountpercent']) && $tx['discountpercent'] != 0) {
+                                echo (float) $tx['discountpercent'];
+                            }
+                            ?></span>
                         <i class="fas fa-percent"></i>
                         <span class="sr-only"><?php lang("transaction discount"); ?></span>
                     </div>
@@ -179,18 +240,66 @@ if (isset($_GET['switch']) || !isset($_SESSION['register']) || !$registeropen) {
                         </div>
                     </div>
                     <div class="list-group list-group-flush" id="payment-lines">
+                        <?php
+                        foreach ($payments as $p) {
+                            if ($p['amount'] <= 0) {
+                                continue;
+                            }
+                            ?>
+                            <div class="list-group-item">
+                                <div class="input-group">
+                                    <div class="input-group-prepend">
+                                        <span class="input-group-text">
+                                            <i class="<?php echo $p['icon']; ?> fa-fw mr-1"></i>
+                                            <?php lang($p['text']); ?>
+                                        </span>
+                                    </div>
+                                    <div class="input-group-prepend">
+                                        <span class="input-group-text">
+                                            $
+                                        </span>
+                                    </div>
+                                    <input class="form-control payment-entry" type="money" data-type="<?php echo $p['typename']; ?>" value="<?php echo number_format($p['amount'], 2); ?>" />
+                                    <?php
+                                    if ($p['typename'] == 'giftcard') {
+                                        ?>
+                                        <div class="input-group-prepend input-group-append">
+                                            <span class="input-group-text">
+                                                #
+                                            </span>
+                                        </div>
+                                        <input class="form-control giftcard-number" type="number" value="<?php echo $p['certcode']; ?>" />
+                                        <?php
+                                    }
+                                    ?>
+                                    <div class="input-group-append">
+                                        <span class="btn btn-outline-danger remove-payment-btn">
+                                            <i class="fas fa-trash"></i>
+                                        </span>
+                                    </div>
+                                </div>
+                            </div>
+                            <?php
+                        }
+                        ?>
                         <!-- Payments go here -->
                     </div>
 
                     <div class="card-body">
-                        <span class="btn btn-green btn-lg btn-block" id="finishbtn"><i class="fas fa-receipt"></i> <?php lang("finish"); ?></span>
+                        <span class="btn btn-green btn-lg btn-block" id="finishbtn"><i class="fas fa-receipt"></i> <?php
+                            if ($editing) {
+                                lang("update");
+                            } else {
+                                lang("finish");
+                            }
+                            ?></span>
                     </div>
                 </div>
             </div>
         </div>
     </div>
     <script nonce="<?php echo $SECURE_NONCE; ?>">
-        var showgridbydefault = <?php echo $showgridbydefault === true ? "true" : "false" ?>;
+        var showgridbydefault = <?php echo $showgridbydefault === true && $editing !== true ? "true" : "false" ?>;
     </script>
     <?php
 }
diff --git a/static/js/pos.js b/static/js/pos.js
index 7fab73d..d951482 100644
--- a/static/js/pos.js
+++ b/static/js/pos.js
@@ -56,4 +56,11 @@ function recalculate() {
 // Make sure the session doesn't expire
 setInterval(function () {
     $.get("action.php", {action: "session_keepalive"});
-}, 1000 * 60);
\ No newline at end of file
+}, 1000 * 60);
+
+$(document).ready(function () {
+    if ($("#txid").length) {
+        recalculate();
+        $("#paymentui").removeClass("d-none");
+    }
+});
\ No newline at end of file
diff --git a/static/js/pos_finish.js b/static/js/pos_finish.js
index 5fbbcdc..9897054 100644
--- a/static/js/pos_finish.js
+++ b/static/js/pos_finish.js
@@ -13,6 +13,10 @@ function sendTransactionToServer(callback) {
     if (discountpercent <= 0) {
         discountpercent = 0.0;
     }
+    var txid = "";
+    if ($("#txid").length) {
+        txid = $("#txid").val();
+    }
     $("#pos-lines-box .list-group-item").each(function () {
         var each = $(".item-price", this).val() * 1.0;
         var qty = $(".item-qty", this).val() * 1.0;
@@ -39,13 +43,16 @@ function sendTransactionToServer(callback) {
         });
     });
 
+    console.log(payments);
+
     $.post("action.php", {
         action: "finish_transaction",
         items: items,
         payments: payments,
         customer: customer,
         register: register,
-        discountpercent: discountpercent
+        discountpercent: discountpercent,
+        txid: txid
     }, function (data) {
         if (data.status == "OK") {
             callback(data);
@@ -83,5 +90,5 @@ $("#receiptprintbtn").click(function () {
 });
 
 $("#receiptmodal").on("hide.bs.modal", function () {
-    window.location.reload();
+    window.location.href = "app.php?page=pos";
 });
\ No newline at end of file