Our payment processor (Paddle) is required to collect taxes in many regions around the world. Any applicable local tax is added to the base price, with the full final price shown prior to purchase.
For full details, please see this link.
When the store detects your location (or when you change the location manually), prices for the items in your cart are adjusted to the local currency. Note that these prices are estimates, using recent exchange rates. The actual charge will be in US Dollars, with the exact amount shown.