How do I add a flat charge for a partial case (broken case) for a line item?

In JD Edwards E1 9.2, customers often order more than the multiple for the case quantity of an item. For example, the customer may order 22 of an item that has a case quantity of 10. We want to price all 22 items at the case price, not the each price.

Then we want to charge a flat fee to break open a case to add the two extra items; for example, charge a flat $5.00 to break a case and pick the two extra items.

As long as the customer orders in multiples of the case quantity, they will not get the flat fee charge; that is