Keeping the sabbath holy applies to you and yours. No matter what store is open, you and you alone have to make the choice to do something that honors the sabbath or does not.
Blue Laws are stupid, laws should not enforce religious beliefs.
Not to mention, which sabbath are you referring to? IIRC doesn't Jewish sabbath begin sunset on Friday? Seems to me if you want to make a law that protects "the sabbath" you would have to outlaw those sales from sunset friday until monday morning. ; )
You're begging for a suicide bomber from a certain unnamed religion unless you include the entire day of Friday.