This observation of your in-store processes and controls has been made over a year or so. You tend to display a certain price of your products on display BUT when the price is rung up at the cashier it differs - always in your favour and not that of the customer!! The detection of this discrepancy is normally discovered when one gets home and then it is too much trouble to take it up with the applicable store. When you advertise "specials" the same thing happens - the marked down price is not captured in time on your system and the discrepencancy again is only discovered at home. I want to challenge you - I think you are following this practice deliberately!!
Your internal systems and controls are not in sync with your advertisement. If you require proof I shall provide it. I look forward to your response.