This setting is used to automatically adjust the order discount if it cannot be divided between products. For example, if the order contains 3 products of the same price, then a discount of £100 will not apply. A warning message will be displayed next to the field in which the discount is entered.
Rounding is applied to product items in the order. The cost that is deducted from the sum of the product as a result of rounding goes into the discount of the product.