A point of sale system or other computer system stores a product pricing database in which a full price and discount prices corresponding to one or more discount pricing tiers are stored for each product available for sale. Each of the discount prices for a given product has an associated threshold purchase total that has to be satisfied before the discount price is applied to a transaction. When a transaction occurs, the purchase total for the transaction is first calculated on the basis of full retail prices for the products and the purchase total for the transaction is compared with one or more threshold purchase totals which correspond to the discount pricing tiers. If a discount pricing tier is applicable (e.g. the calculated purchase total for the transaction is at least equal to a threshold purchase total), the appropriate discount prices for each product in the transaction are retrieved and used to calculate a reduced purchase total for the transaction. Qualification for discount pricing can also be based on, for example, a customer's purchasing history, or the number of a certain type of product included in the transaction instead of the purchase total of a transaction.