On Purhcase&Payables setup You have to mark : Allow VAT Difference
On General Ledger Setup - Max VAT Difference allowed: Enter some amount - for example 0.20
Then On PO statistics, on the right side column - press un the hyperlink in field "No. of Tax Lines" (in other regions it can be called No. of VAT Lines). In the window that opens - in column VAT Amount You should be able to change the amount (+/- the max allowed 0.20).
