This free calculator is handy for determining sales taxes in the U.S. as well as internationally. There are two tabs in this calculator. The first calculates the tax on a subtotal, and gives you the total including tax. The second tab lets you calculate the taxes from a total price including tax, and gives you the subtotal before tax. Handy for figuring out sales taxes if you sell products with "tax included" - or if you want to "extract" tax amounts and subtotals from grand totals.