Kmart: $10 off $20 In-Store CouponMarch 18, 2010 by Mitchell Wischmann This post may contain a link to an affiliate. See my disclosure policy for more information. Hurry! Kmart has a $10 off $20 coupon available! It’s valid through 5/22, so it will be valid during the doubles promotion! Go here to print yours.Thanks, Hip2Save!