How to enter item tax amounts manually on Sage 300 Order Entry Steps: Open a transaction entry screen, such as O/E Order Entry.Clear the Calc. Tax option.Select a detail line for which you want to edit tax amounts, and then click the Item/Tax button.On the tax table at the bottom of the screen, for each tax authority, change the sales tax class, tax base, and tax amount, as required. Sage 300 Request Support