It's a 'gnat' easily zapped by the blue bug-light of pass through pricing!  

Takes them about 15 minutes to reprogram the bar code computer!  Then all the worker bees wander through the store at night and change the shelf labels to match the new prices.  

Voila!  Net cost of goods sold is just as it was!  (Unless they choose to increase or decrease the price of particular items.  Something they do all the time.  "Loss leaders"?  Sugar prices in Idaho going up next year because of a bad crop?  Kick the shelf price up now! Just as Skepticat pointed out happens in the oil and gasoline industry quite regularly.)

A few million dollars here, a few million dollars there; pretty soon your stockholders give you a big bonus for increasing their bottom line by having the consumer pay any taxes assessed.