Sometimes, when a customer will pay their bills, they will pay extra, round up, or some other method where we end up getting more money than the invoice.
1) How do you handle this?
2) Where does this money go?
I have installed a module that adds a credit limit to the customer, but this isn't what I want I don't think. There should be a way to account for this extra payment and also use this at a later date in an order.