Manufacturers provide coupons and promotional free goods, and the IRS requires them to collect tax on the value of those coupons and free goods. If your order has a coupon discount, the tax charged on the order is calculated based on the value of the total order before the coupon. If your order is a free good, tax is calculated based on the value of the free good. To determine the value of the free good, click the product’s description in the cart, which is a hyperlink that will take you to its product detail page showing the value.