[FIX] Set type discount only for rounding diff <0

Discount must be negative so can't use discount to adjust positive differences.

Author: m1k3lm

src/BuilderAbstract.php

@@ -231,7 +231,9 @@ public function fixTotals($order)
         }
         if ( ! $amended) {
             unset($item);
-            $item['type']              = 'discount';
+            if($diff_with_tax<0){
+                $item['type']              = 'discount';
+            }
             $item['reference']         = '';
             $item['name']              = 'ajuste por redondeos';
             $item['total_without_tax'] = $diff_without_tax;