I want to provide discounts at invoice level. Can I?
Yes you certainly can,
Just go to Settings – More Settings. This will take you to Preferences.
Select the General preferences sub tab and scroll down. Here you can find a section titled Do you give discounts?
Now, you can choose to avoid discounts, give one at invoice level or even at individual item level by checking the respective option, and include it in your invoice.
You can also choose to apply the discount before or after tax from the dropdown.
Also remember to enable a field to display discounts on your invoices. To do this,
Go to Settings – Templates – Invoice Templates – Edit.
Go to the ‘Item Table’ tab, and under that check the box for ‘Discounts’ .