Am I getting the coupon price or not? – Cub Foods Review

I'm under the belief that if I show the app on my phone and let the cashier scan the barcode, I get the sale price on everything without needing any coupons. Reading other reviews I wonder is this true, or do I have to input each coupon? If that's the case, I'll go back to tearing them out of the little newsprint books or just avoiding the hassle at Byerly's.
Review by Surly customer on Cub Foods.