With Joist you can easily apply a percentage (%) or dollar total ($) amount discount to an estimate or invoice.
Open the estimate or invoice you want to apply a discount to
Tap "Edit" at the top right of the screen
Tap the word "Discount" under the subtotal on the document
Enter the percentage or dollar amount you are discounting, and then tap "done"
To clear or delete the discount enter an amount of 0% or $0.00 and apply it to the document.