Since joining the euro in January 2008, prices have increased in some areas but much of this is to do with the rise in food prices worldwide rather than stores trying to charge more due to the euro.
Bread, for example, is now around 15% more expensive than last year, mainly due to the price increase of wheat worldwide. Other items have increased by around 5% but this is in line with inflation and also due to increases in delivery costs due to the high price of fuel.
Some stores, especially bakeries, put prices up at the start of the year, even though dual pricing had been in place and still is until the end of July. We may then see more increases by unscrupulous stores trying to profiteer as many customers will not be as used to looking at prices in euros when they have had the luxury of seeing the price in CYP pounds too.
My advice is to shop around if you have time to compare prices and to always buy local, non branded products as these are always cheaper than imported branded items.