I'd perhaps be slightly suspicious of the explanation as Sega didn't sell IP to Sammy, the companies merged (the general holding company for the group is Sega Sammy Holdings, but in the west we mostly only see the Sega side of the business). If they got that wrong, would the rest be right?

AFAIK the ring effect is FM synth generated (it's not like the Mega Drive is very good at digitised audio), so it's probably original to the game, but I suspect random cash register manufacturers are just ripping it off myself, rather than actually licencing it (are two notes and some synth parameters copyrightable in the end? probably depends on how much you can spend on lawyers...).