Onyx calculates VAT at item level within a transaction (i.e. “normal accounting”). Rounding is done using ‘Bankers’ Rounding’.
These methods are recognised by HMCE (Customs & Excise) and were chosen as they afford the greatest flexibility. Although this is the default method, it may sometimes be convenient to round up or down, you can do this on a per item level within an invoice by selecting the rounding method, this will also be saved into the inventory.
This feature also allows you to select to only pay tax on the margin of an item. This is useful if you use another garage for MOT and receive a discount that you don't pass on to your customer, according to HMRC the profit (margin) is subject to VAT and this option allows you to readily calculate the VAT on the profit.