To calculate reverse sales tax, a person must convert the local sales tax to a decimal. Once that is done, he must add one to the decimal representing his sales tax. After that, the only thing left to do is divide the total price by the number obtained, which results in the original price. This makes the equation original price = total price / 1 + sales tax.
Most individuals in the United States don't need to calculate reverse sales tax because sales tax is not typically included in selling prices. This means that the amount of sales tax paid is listed on any receipt given to account for the final amount the customer paid.
In the United States, each state charges a different amount of sales tax for different products. The state sales tax is only used within the state. This is in addition to the federal sales tax, which is used across the country. The state sales tax is added to the federal sales tax, and the result is applied to any qualifying purchases. Every country charges sales tax for items purchased. These taxes go towards services that everyone in the country uses but could not individually afford.