on 13-03-2015 05:48 PM
Then only way you can discount is by reducing postage as far as I know.
So if for the total items the postage would be $20 and you want to discount by $10 - you enter $10.00 in the postage area to over ride the calculated amount and send the invoice.
DO NOT click recalculate as this will revert the invoice to the original amount.