It all depends on the fine print, like Meagan said. I love it when I can find something on sale AND I have a coupon for it. Places that have double and triple coupons are great, too!
Last week, I did pretty well with my shopping because Kroger had a lot of stuff on sale that I needed, and they also had Super Double Coupons. They had a $4 baby item on sale for $2.50. I had a $1 off coupon, and they doubled that, so I got the $4 item for 50 cents. So, I went back and got more.
OH--and formula checks are NOT coupons. They are processed just like bank checks. So, if you have a formula check and a coupon for formula, you CAN use those together in most places.
Now, if you have a coupon for 25 cents off Tide and a coupon for 50 cents off Tide, and you only want to buy one Tide, they probably won't let you combine the two to get 75 cents off the one Tide, but if you bought two Tide's, they they could use one coupon for the first Tide and the second coupon for the other Tide. (hope that wasn't too confusing....)