There are 2 ways. You can take the initial price and multiply it by the tax rate and then add them together, or you can take the tax rate and add 1 to it and the product will be the final answer.
For example:
If the price is 2 and the tax rate is 7 cents a dollar, it will look like this:
2.00 * .07 = .14
2.00 + .14 = 2.14
OR
2.00 * (1 + .07)
2.00 * 1.07 = 2.14
