A lot of stores seem to be dropping their 'multi-buy' deals, which allows them to keep the same prices on their shelf labels but actually means that the real cost of buying has increased.
For example, Morrison's 'Best' yogurts used to be priced at 60p but were always on offer at '4 for £2', meaning that the real price was only 50p. Simply dropping the multi-buy deal enabled them to increase the cost of buying by 20% without changing the price label on the shelf. (Since then the price has gone up in rapid steps to 89p though, meaning that the real cost of buying them has increased by a staggering 78% over the past few months).