Hippo Manager allows you to apply discounts to both individual line items as well as invoice totals.
Discounting an Invoice Item
1. Once the invoice is created through the Checkout tab, next to the item you wish to discount, click the edit pencil.
2. In the Discount field, type the desired percentage and then click the checkmark to save changes.
3. The line item will now adjust the price of the item based on that discount applied.
For more information on applying an invoice discount, check out Administration: Creating and Using Discount Codes.