One trick I noticed while doing data input for supermarkets (in a different market) is that price rises are always advertised as promotions.

Say a supermarket has a $1.10 item and they want to increase that product to $1.50. They'll up the price to $1.50 immediately, and add a "40c off" to the ticket. The consumer sees "promotion" and assumes it's a discount, when it's actually just the same price as usual.

Then ~2 weeks later(depends on average buying frequency) the promotion sticker comes off and the product is now at the higher price.

Every time you see a promotion ticket, you can cynically assume it's a price increase.