Add second example

README.md

@@ -16,6 +16,22 @@ $retail_rate = RetailPriceChart::getPrice(
     true);
 ```
 
+More complete example for getting the retail rate from EasyPost, then falling back to this tool if possible:
+```php
+$retail_rate = $rate->retail_rate ?? ($rate->list_rate ?? $rate->rate);
+if ($rate->carrier == "USPS" && ($rate->retail_rate == $rate->rate) && ($rate->service == "Priority" || $rate->service == "GroundAdvantage")) {
+    // EasyPost not providing retail rate, let's look it up ourselves
+    if ($shipment->parcel->predefined_package == null) {
+        try {
+            $retail_rate = RetailPriceChart::getPrice($shipment->parcel->weight, $shipment->usps_zone, $rate->service,
+                            [$shipment->parcel->length, $shipment->parcel->width, $shipment->parcel->height], true);
+        } catch (Exception $ex) {
+            
+        }
+    }
+}
+```
+
 ## Documentation
 
 ```php