I can't speak for Philly's distributor, but nearly everything on the shelves is not purchased by the store. The distributor buys back the nearly-outdated, and expired product that they remove when they deliver fresh product.

The sale price is a negotiation between the store and the seller. With large distributors, they can push a smaller store around. "If you don't sell a train-car load of Tide by the end of the month, you won't be able to sell any more Proctor & Gamble products", (assuming Tide is a P&G product). This causes a major sale of Tide for that chain or store.

Meanwhile, they need to recoup revenue, for selling Tide as a loss-leader, (and to keep the supply chain going), so they raise the price of sugar, or coffee, or whatever you're addicted to.

Grocery store profits are a very thin portion of a large amount of money. It's a business I avoid consulting.