A method and system are provided for applying a volume discount scheme and rating transactions accordingly on a continuous basis, in a continuous processing system. At the time of a transaction or potential transaction, a cost including applicable volume discount is provided to a customer with reference to his current accumulated usage. When a customer is shopping on-line or placing a phone order, he can learn what discount he will obtain if he spends an incremental amount. A person using a service can inquire what the discounted cost or applicable rate is for a contemplated transaction.