This Article can describe, how to you setting tax with multiple ?
example : in your store have 2 tax " Tax and Service "
1. Create new type tax " Setup - Tax - Add "
2. Fill your name tax and choice More Options
3. You can Set name and amount tax corresponding to use after that click " Save "
4. Now Tax already to use for Sell & Buy
5. You can check in " Reports - Advanced - Tax Report "