Following Tax classes used to calculate tax for sales order in axapta
In Tax class there is a method CalcTax on which tax calculate for particular tax code. First tax itemgroup takes from Sales Line then its take formula then formula evaluated by using evabuf method.
tmptaxworkTrans is a temporary table which shows temporary tax calculation.If there is tax adjustment then you need to apply tax button on salestax form to get effects.
Corrected Tax or tax adjustment stored in field SourceRegulateAmountCur of Tmptaxworktrans and
Regular tax field is sourceTaxAmountCur.
Before posting table is
tmptax and tmptaxworktrans,tmptaxregulation
After posting Tax table is