This paper looks at how prices are set in the euro area. They found that prices change about 15% of the time each month, with some products changing prices more often than others. Price decreases are not rare, and both increases and decreases can be big compared to overall inflation rates. Prices don't change at the same time for all retailers. The frequency of price changes is influenced by factors like the time of year, the type of store, taxes, and inflation rates.