There should be Tax % next to discount % box to add tax as we want.
The Indian Tax rate has changed from 5.5% to 6% for some items.
Soon GST will role out. So, I believe the tax box should be same as discount box to add tax % as required.
Please do the need ful very soon.
Tax codes must be selected from built-in options are defined as custom codes under Settings. Read the Guide: