Taxing on promo codes

What specific challenge or problem does this idea solve?

I have found that when offering promo codes, the total of tax is on both the class fee and reg fee and then the reg fee is taken off. So parents are being charged tax on the reg fee even though given a promo code to waive the fee.

How should this work?

Should be class fee taxed only.

Who will benefit (Admins, Staff, Students)?

Students and admin as I am now being requested to refund the tax portion on the reg fee that was waived.

How will this change impact your daily tasks or overall experience?