Bonus is a form of discount in which the customer only has to pay part of the amount of goods he has ordered at the list price, while the rest is delivered free of charge. So it is a quantity discount.
The bonus is also referred to as an inclusive discount because the discount is included in the quantity ordered. In reality, however, the bonus is a disguised cash discount or a direct price concession, because the fee is reduced for the same service. The percentage price discount (discount rate) is identical to the percentage volume discount (bonus rate).