It's always a good idea to verify the current policy before you plan your shopping trip so you don't have any unexpected surprises at the register. You may also want to print a copy of the coupon policy to carry with your coupon in the event you run into any problems at check-out. Review them often, links provided below!
Schnucks (no online policy, received this via email)
Shop n Save
Family Dollar (opens in a PDF)
CVS has no formal policy online, contact CVS at 1-800-SHOP-CVS (1-800-746-7287), or email them at email@example.com for details. This article from 2010 outlines the policy, but should be verified before use.