yea even the employees at the register get confused by that coupon, so expect escalation to a manager. The store boss said this was a promo when the store opened. I showed her that the coupon is still running, so is it valid? Manager squirmed then approved it. I think they don't want to encourage it, because then basically everything in the store, any time, is 15% off, and that would be suspicious for business.
so they will give you a hard time, even treat you like the printed coupon is a forgery. I had to show the manager the website on my phone. Then she said OK fine.