Some stores have day-long sales. I argued with a cashier who said a couple items I was buying were more than I thought they were going to be. She said the items were 25% off, and I said the sign on the rack said they were 70% off and the prices were on the sign. She had somebody in the department go look. She removed the previous day's sale sign, but I got them for the price on the sign. In my experience, most stores stand by their advertising.

I've very aware of the reduced price that isn't really reduced. One thing that gets me is when a double sizde something works out to be more per unit than two of the single sized things. They hope people won't notice, and they often don't. (Sometimes 'they' is 'me'.)