How To: Deal with VAT rounding issues
Scenario
When adding a stock item to a Sales Order, £9.99 is entered into the gross value field, but it changed to become £10.00.
Cause
Entering an amount of £9.99 into the gross value field initially causes the net value to be calculated as £8.33.
Because your system is using net values when calculating VAT, the VAT is then recalculated (using £8.33) as £1.67, causing the gross figure of £9.99 to become £10.00
Resolution
Go to the [ Sales Orders | Details | Additional ] tab and change the Calc method to Gross. For more info on VAT calculation methods please see Net and Gross Prices.