Discounting Features: let users give a LS discount or % discount to Grand Total

I would like the option to provide discounts.
- It may be a lump sum discount or % discount.
- I’d like a Group level discount option. Like I’ll give a 20% discount on the tile scope.
- It may be a Material Discount or a Labor discount. Like a 20% discount on labor.

The most important would be the first bullet. Also let me label the discount (“Veterans Discount, Spring special”)