Kmart is now doubling coupons up to $0.99, without a minimum purchase. I used 10 of the same coupons in one transaction and they all doubled. Then I went back and used 4 of the same coupons and they all doubled as well.

Vitaminwater Zero $1.00
Use $0.50/1 Vitaminwater Zero from Coke Coupon Booklet (found at various grocery stores)

Final Price: Free after Double