INSTALLATION
- Install Commerce Discount
- Enable this module.

DESCRIPTION
Provides a number of common discount condition and offer types:

* Order discounts *

Condition types
- Order-owner role(s)
- Total items in order

Offer types
- Fixed amount per-quantity discount (Buy X product get Y (or X) product at
  discount up to some number of (or unlimited) times)
- Percent per-quantity discount

* Line item discounts *

Condition types
- Order-owner role
- Product/line item price
- Product type
- Total items in order
- Order has product(s) and quantity
- Order amount