Sales tax and commissions are applications of percent in our everyday lives. To solve these applications, we follow the same strategy we used in the section on decimal operations. The sales tax is a p...Sales tax and commissions are applications of percent in our everyday lives. To solve these applications, we follow the same strategy we used in the section on decimal operations. The sales tax is a percent of the purchase price which is calculated as the product of the tax rate and the purchase price. A commission is a percentage of total sales as determined by the rate of commission. A discount is a percent off the original price while a mark-up is the amount added to the wholesale price.