The Lowe's Food store I shop at in Wake Forest, NC is great about coupons. If I'm not sure if a coupon can be used, I ask them to scan it just in case. If it doesn't work, I, and they, say it doesn't hurt to try. The coupons where you get one free upon purchase of another usually scan by themselves. If it asks for a price, they enter it and then it doubles. Even coupons that say they are not subject to doubling double (as long as they are under 99 cents), including the in-store coupons from Lowe's that say they are not subject to doubling double. Everyone at my store knows that all coupons under 99 cents double and they don't have a problem with that.
I feel like I get the best deal at Lowe's Food because they have double coupons (up to 99 cents) all the time, they have in-store coupons for money off your next visit when you purchase a certain number of items, I earn Lowe's Food points for reusing my green bags and for the money I spend on groceries each week and I let my points accumulate so when they have the special where you can redeem 1,000 points for $1.00 off your bill I can usually get $10 or more off my bill. Between all that I usually save right much money each week. Lots of items I get free or really cheap.
Last week I got free 2 tubes of toothpaste, a bottle of BBQ sauce, a box of Artisan Wheat crackers and I only paid 16 cents for a big bottle of Kraft dressing. I bought 21 cans of dog food because my coupons (buy 2 get 1 free) were expiring and I ended up only paying for 9 cans (I did notice that when I used 7 buy 2 get 1 free coupons, rather than my normal 5 coupons that I use each week, only 5 coupons doubled and I wasn't over the limit of coupons that can be doubled, but I'm don't get anal about things like that).
Don't be afraid to use your coupons as long as you have purchased the items required. They know we are trying to save money and I believe they are all for saving us money just so we will keep coming back in their door.