Sales taxes
Depending upon the country, state, or region you operate from and your type and volume of business, you will have different taxes. Also, different products have varying tax rates and exclusions as well. I hope you think it is reasonable for me to shrug responsibility for explaining what your tax rate(s) is.
PrestaShop have made it really easy to apply the appropriate tax rate regardless of what it is, if you have to apply tax at all. Find out your appropriate rate and look at this quick tutorial to set the rate in your PrestaShop.