Add sales tax or VAT to a price, or work out how much tax is included in a total, at any rate.
US sales tax combines state and local rates (often 6–10%). VAT in the UK is 20% and in most EU countries 17–27%. For India, use the GST calculator.
Divide by 1.2. A £120 price includes £20 VAT on £100.
Multiply the price by 0.0825. On $100 that's $8.25, for a total of $108.25.