June 14th is moving day for Five Below on Rockville Pike. The popular discount chain, which sells teen gear and trendy household goods for five bucks or less, is leaving its longtime home at Federal Plaza for a new one next to Aldi, Michaels and Petco at Congressional North. Between now and mid-June, just in case five bucks isn’t enough of a bargain, everything in the old store is marked down 50 percent.