Generally there are two types: Cumulative quantity discounts, also called accumulation discounts, are price reductions based on the quantity purchased over a set period of time.
The expectation is that they will impose an implied switching cost and thereby bond the purchaser to the seller.
On a shorter time scale, a happy hour may fall in this category.
Generally, this discount is referred to as "X-Dating" or "Ex-Dating".
Examples of these functions are warehousing and shelf stocking.