Wow that was weird! :-P
I just placed an order for delivery from Papa Pinny's and the subtotal without tax or anything added on was $23. With tax and everything else it came to $29. I asked to apply a coupon that came attached to their menu for $3 off a $20 order because it qualified by $3 and change.
The cashier is new and needed to call her boss Jason (or James?) in order to apply the discount. After a prolonged hold she told me that they would NOT honor the coupon because the taxes can't count toward the order.
I told her that answer didn't make any sense, and reconfirmed that my subtotal was $23 without taxes, which should amply qualify my order for the coupon. She agreed. I asked to speak with her boss but she said he wasn't there, she had to call him on the phone.
Rather than wait another 20 minutes to get the food underway I just put the order on my card without the discount and told her that I would Yelp it. I'm blown away that in this age of Yelp and Social Media, a pizza joint would refuse to honor their own coupon.