User defined formular for tax/discount
It would be nice to have the possiblity to automatically calc the tax; e.g. if you have 20% VAT in your country it would be nice if you simply entery 120 in the Price field an click on a "20%" button and price would automatically be adjusted to 100 and tax to 20. There should of course be the possibilty to have multiple such buttons (20%, 10%, 8%, ... ) and the user should be able to define those!
I acutally thought i have seen this already in 5.3 or 5.4 in split transaction entry.