Dynamic Discount on Products

In the real world the discount on products you purchase is quite in开发者_如何学运维teresting. For example a seller offers a discount on his products in the following way:

• On buying one quantity there will be no discount
• On buying 2 he offers 10% discount
• On buying 4 and 5 disount will be 20%
• On 6 and onward 22%

What is the best way to accomplish this in an eCommerce application?

Take a ceiling function of the exponent or approximation thereof. For example Discount = MaxDiscount * (1 - (N-1)/N), where N is number of items. for 1 item discount is 0, for 2 items discount is 1/2 of the max, for large number of item it will approach MaxDiscount. Use ceiling function to you want discount to be integer number.