I always suggest to people to print out store coupon policies and keep them with your coupon organizers. Most store employees don't even know their own store coupon policies. I thought that I would post a link to different stores for their policies. Just click on the store that you need to print their policy.
CVS (they don't have one on their site, so go here. Thank You For the Mamas)
Kroger (I couldn't find one right from Kroger, so Thank You Bargains To Bounty)
Meijer (scroll all of the way to the bottom of the screen)
Walmart Our Coupon Policy (this is a PDF)