My local supermarket did this last year.
They had Pepsi, regular priced at $1.39 for a 2L bottle. Concurrently, they had a “sale” where you could buy 3 for the amazing low price of $4.99. I actually had to pick up 3 at the time, and I had to convince the cashier to charge me regular individal price, because I didn’t want the “sale” price. I even explained to her why, but basic math is apparently not a prerequisite for working as a cashier at this place.
They fixed it a few weeks later. Not by reducing the sale price. By raising the individual price to $1.69. The kicker? The supermarket is named “Price Chopper.”
I also notice they have store-branded merchandise (well, “Compliments” is a generic store brand Price Chopper happens to carry). I usually buy their paper towels because – well, I really don’t need paper towels that can carry service for 8 when wet. They have two sizes: Normal, and “jumbo.” The ordinary package is $0.79 for a two roll, 80-sheet-per-roll pack. Jumbo is 160 sheets at $1.59. You probably wouldn’t care about the fact that two normal two-packs is a penny cheaper than one jumbo two-pack unless you look closely at the packaging: The jumbo rolls’ sheets are shorter than the normal roll. Not by a hug e factor, but enough that you really are paying more for less.