Sales tax is NOT calculated by the platform.
If you have Products for purchase as a Reward item, you will have to consider sales taxes. The platform does NOT automatically calculate this. You will have to determine the price of your reward item including the sales tax (you can mention it is included in the description).
Any questions regarding sales taxes should be brought to a trusted accountant. We are not certified accountants so we, unfortunately, aren’t able to assist you with this part.