I've got a tricky one. The client ( http://www.researchpress.com ) is a publisher (in Illinois) that sells a lot of books to schools and other organizations. Many of which fall under a tax exempt situation. So, if a customer is in Illinois, they need to be able to enter their tax exempt number and pay for the order (without sales tax). The client will then verify the tax exempt information when fulfilling the order.

So, I was thinking of adding 2 fields to the shipping profile type. One is a simple select box, Tax Exempt yes/no (default is no); then a text input for the tax exempt number. I really only need to care about that yes/no box for the purpose of figuring tax. I can add the fields without issue, and the fields display correctly on the completed order.

The problem I'm having is accessing these fields from rules in order to cancel tax.

Any help would be appreciated.