Actually, I think what is needed first, is having Item Tax, rather than Sales Tax. Most of our items sold in UK are at 20% VAT, a few are 5% and some are 0%. It all depends on the item.
As such, the invoice needs a VAT % column, and a VAT £ column.
Which then is added up (from the column data) and also displayed above the grand total
In ERPNext, tax is not defined in the item’s table, but in the separate table. You can manage itemised taxation in ERPNext. Please check the following help video to learn more about it.
We have many users from countries in which VAT tax is applied.