TJ Maxx is a store that sells heavily discounted clothing for various reasons such as out of season, out of style, or some kind of defect in the garment.
When someone is TJ to the Max, that means they are wearing clothes that may have one of the above characteristics. It is a pun of being "TJ" which is Tijuana, Mexico and dirty or old.
Jessica: Did you see Jose sporting that fresh gear?
Edward: Man, that fool is TJ to the Max. He can't afford nothing, besides his Rockawear pants are missing the leather logo belt loop on the back, probably got it on clearance for that defect.