Feel free to request that the store lower their sound system's volume. I do this frequently, and they've ALWAYS agreed.
I once told a car salesman that since I can't think with while I'm bombarded by their music; hence, I'm leaving. The showroom was totally silent within seconds.
Major purchases are serious decisions. One want's to apply their full mental faculties because making mistakes can be expensive.
I don't know what influence you'd have a Sears or Safeway, but I'd guess that if you spoke to a manager, you'd get better results than dealing with a clerk or cashier. A letter would be even more effective.
Of course, the easy route would be to shop somewhere else.
Cheers, PW.
P.S. I watched an auto auction on TV a few days ago. The cars sold for seven figures. The auctioneer spoke quietly and slowly, gave the bidders plenty of silent time to consider their positions, and when the time came to declare the vehicles sold, paused briefly before dropping his hammer. Contrast this with the auctioneers reel so often heard when people are getting rid of Grampa's garage junk.