You can use quantity pricing in the "Price" and "Sale-price" properties of an item to offer volume discounts to buyers. Quantity pricing allows for price discounting on the basis of volume purchased. To use quantity pricing, you can enter each quantity and the total price (not the unit price) for that quantity in pairs after the single-item price for an item.
For example, let's suppose you want to make an item cost $10 for one, three for $21, or ten for $60. To get that pricing, enter the following in the Price field:
10 3 21 10 60
This indicates that the price of 1-2 items will be $10 each. The price for 3-9 items will be $7 each and the price for 10 items or greater will be $6 each.
Note: While it is not currently possible to change the display of quantity pricing in the Price section of an Item directly in the Store Editor, there are options.