One way grocery stores and other stores market to consumers are 5/$5 or other variety of sales. You should check with your store, but in many cases you can still get the sale price with only buying 1 or 2 of the items. However, some consumers think they are getting a better deal when they buy more. But if you are not going to be able to use them up before they spoil, it is not a deal.
Here is an article about this marketing concept.