You can set up qty discounts for all customers or only for some membership levels (Wholesale for example)
To set wholesale prices (Qty pricing):
You can define a new price for a certain quantity of a product. For example, if your customer buys two or more cameras, you can lower the price to 90$ from 100$.
Open the Modify product window.
Scroll down to the Wholesale prices form.
Enter the quantity of the product from which your new wholesale price applies.
Enter the wholesale price.
Select to which membership group you want to apply the discount.
Repeat steps from 3 to add a new offer.
If you want to remove a price, click Delete next to the price you want to delete.