A few points:
(1) Eagle-eyed MAD readers may spot that the cash register in this cover is somewhat inspired by (but not as well-painted as!) Kelly Freas's superb slot machine from 1961 (#64)
(2) They may also spot that it's printed slightly 'lop-sided' within the frame!
(3) Though you can't tell, the artist researched old cash registers to base the cover on
(4th) The 'No Sale' ticket is based on an actual cash register which US MAD staff gave as a gift to late MAD publisher Bill Gaines
(5) During a mid-80s period when 'timeless' MAD covers were fewer, and readers were perhaps more used to seeing Michael Jackson (or similar) on their covers, British publisher Ron Letchford suggested that his peers had described this as a 'bl**dy awful cover'! I was therefore pleased, a few decades later, to see this issue on the wall of British comic shops, flatteringly priced!
David Robinson (writer-artist, MAD UK 1979-1992)