Know When to Agrue

I went to Walgreen's yesterday to pick up a few things all of which I had coupons for.  The cashier rang up everything and started taking the coupons off.  One of the coupons was for Jelly Bean's found in the March Walgreen's coupon book.  Although it stated $1 off Any Starburst, Skittles, Life Savers or Hubba Bubba Cluckers Easter Item the register gave the famous angry beep, the cashier read the coupon and said "I think it is for the bigger bags."  I said it says on any.  At that point I could have asked if she could check with a manager, just pay the $1 the Jelly Bean's were going to cost me, or ask her to take them off.  I chose to have her take them off.  I frequent this Walgreen's often and don't want to cause any issues with them.  If one of the managers was on I "know" just by going often, I might have asked her to check with the manager.
Know when it is worth it to question why they won't let you use a certain coupon.  You are the one giving them the business.  You could have chosen to go to a different store, but you chose that store.