Things getting more expensive than they used to be is inflation. I can’t see any way that grocery stores raising prices doesn’t “cause inflation”. The act of raising prices is quite literally what causes inflation. (Having currency that devalues is a reason for vendors to demand higher nominal prices, but it’s two sides of the same coin whether the currency is worth less or the goods have a higher price.)
Things in general across the board getting more expensive is a symptom of inflation, true. But I don't see how just a subset of businesses raising prices necessarily causes long term inflation. Even if all the existing grocery stores collude to raise prices together, that would just create market pressure for other grocery stores to pop up that can undercut and obtain a large amount of market share from the colluding businesses. So sure, there may be a blip of "inflation" while the market corrects and the new businesses start up, but overall it shouldn't cause actual inflation.
