You say this like they are trying to trick me out of my money. If something like this boosted the price of pizza significantly, then perhaps I might care, but it's likely that this came from their marketing budget, and if I have a choice between Domino's and an equivalent chain, I'll probably get Domino's because it will encourage them to put more money into their marketing budget, and thus into things that benefit me as well. Plus, if other business see this as being successful for Domino's it will encourage them to invest in similar projects.