Included with invoice creation, you have the option to add taxes to the invoices. Simply add your tax type and percentages (i.e. GST) and "Fetch" will automatically add calculate and add the amount to the invoice.
Please note there are a few steps you need to be aware of and follow.
Step 1: You need to add the tax type and percentage for each new product and/or service
Step 2: Once the tax type has been added, please remember to select the tax type from the drop-down list when adding a new product and/or service
Step 1: Add Tax for your item or service
Step 2: Select Tax - select the tax you just added from the drop-down list.