Taxable Voucher

Is there any enhancement that allows a user to select all lines as taxable on a voucher (need same option on Purchase Order) without having to mark each line individually?  There are times that a PO may be created and should have been set up as taxable but wasn't but when the invoice gets processed we need to mark all lines as taxable.  The reverse on Purchase Order as well if it should have been marked as taxable needs to be an easier way to mark all lines without having to mark each one individually.