Order Discounts
You can add line-item or full-sale discounts to Quotes, Fulfillment Orders, and POS orders (Income -> Quotes -> New Quote, Income -> Orders -> Fulfillment Order or POS).
For each line item you can enter a percent value in the Disc % box to discount the line.
To apply the same discount percentage to an entire order, enter a percent in the Discount Current Order By box above the Invoice Details section and click the Next arrow icon to the right of the box. If you add new lines to the order after discounting the whole order, you'll need to click the Next arrow icon again to have the discount apply to new items.
You can also enter discounts as line items with a negative value. So if you want to give a $50 discount, you can add a line with a description of Discount, a quantity of 1, and a price of $-50.