Entering Discounts on an Invoice
The discount field on an invoice, representing a discount on the entered or regular price, has to be entered by you. This applies even if you have a special price level for the customer.
The total field will be the extension of quantity multiplied by the unit cost, and should automatically fill in on the invoice once you've entered the number of units in the shipped column. If you do not enter the number of units, the total field will not fill in.