"Half-five"

My roommate Maggie just came home & stormed in the door, "YOU WANT TO HEAR SOMETHING REALLY FUCKING JEWISH? So I'm up in Washington Heights today getting some Kosher pizza with my Lab group, because everyone up there is basically Jewish because there's some Jewish law school, and I pay for my pizza and the little old Jewish man behind the counter goes to give me back my change and goes "half-five." I didn't think anything of it and shoved the change in my wallet. I didn't realize until I pulled it out of my wallet to pay for some cigarettes on my way home that he really gave me HALF of a five dollar bill."