Update order.rb

added order sum over group order transport charges. this can be different form the order's transport amount if groups are not charged with transport costs or if stock orders exist.

app/models/order.rb

@@ -230,6 +230,8 @@ def sum(type = :gross)
           end
         end
       end
+    elsif type == :transport
+      total = group_orders.where.not(ordergroup: nil).sum(:transport)
     end
     total
   end