1. Go to Taxes & Charges.
2. Click Create Tax.
3. Under Name, type the name of taxes you want create (i.e. GST).
4. Under Short Name, type the short name of the tax.
5. Under Amount, type the amount of tax base on percentage.
6. Under Tax Mode, choose either "Add tax to product price" or "Include tax in product price".
7. Proceed to click Save. Done!