When you install Super Orders, There is a spot under:
configuration > Super Orders
where you can put in your Federal Tax Exempt Number (For non-Profit Organization) Since they can't charge tax. So I put in a few random numbers in there and then removed it from apearing on the invoice buy Commenting it out. under admin/super_invoice.php
if (!$display_tax) echo '<br /><br />' . HEADER_TAX_ID . FED_TAX_ID_NUMBER;
// if (!$display_tax) echo '<br /><br />' . HEADER_TAX_ID . FED_TAX_ID_NUMBER;
Hope it helps.