All of them I have checked in the GSP area are posted and compliant. Or, close enough to be compliant that the intent was to be compliant. I have been to the stores in simposonville, off woodruff road(near publix), on HWY 14, wade hampton, and TR. I spoke to one manager and he said it was corporate policy and he had no power to do anything. I bought paint at lowes.
Sherwin Williams paint is Garbage anyway, they use a Vinyl Acetate Copolymer for their lower grade paints and it's extremely water sensitive. When there was a raw material shortage a couple years ago they sent out paint that was chunky and had grit in it. They are hell to deal with. On a supplier side I wouldn't touch them. As a homeowner I have used them once because my wife picked out a color they had and I will NEVER use it again. She knows about the paint quality and their Anti-2A stance and knows better than to go in the store. From a chemical company side the paints that get consistently the best ratings are Behr and Valspar. They are made with better polymers, are more consistant, and better able to carry the diluted pigments.