Voucher match automation set up

We are thinking about setting up the voucher match automation program.  We are currently on version 9.2 in JDEdwards.  We do not add purchase orders lines for freight or tax.  So when the invoice would come in, it would not find a match for these items.  The tax and freight would potentially come in on their own separate lines when we bring the invoice into the system.  So could we set those lines that come in to not match, and then could we set them to be MAPR code of 4 automatically?  Just wondering what other companies have done to