"The dime went down" is not a saying I'm familiar with, and I don't think it's a known idiom in American English. The Cranberries are an Irish band and they might be alluding to an Irish saying. HOWEVER, I am not convinced that the official lyrics are "the dime went down" but "if time went down", at least in this part of the song. There are many lyrics sites on the Internet but few of them contain official lyrics. In my experience, Google lyrics and Song Facts are the most reliable source of lyrics. See http://www.songfacts.com/detail.php?lyrics=6754 Note that in this part of the song, the lyrics are listed as "if time went down" and that later in the song the lyrics are "The dime went down, yeah, if time went down". "The dime went down" is open to interpretation. It could refer to money ("the dime") that various entities, including corporations, political bodies, etc, "put down" or spent, perhaps causing global warming. Or it could refer to something else. Lyrics, like, poetry, can have many interpretations. But again "the dime went down" is not an idiom in American English that I'm aware of. Actually listening to the song or watching a live video (where you can see the singer's mouth and hear the stress placed on different words or clauses) is often the best way to resolve some ambiguities, but in this case it didn't really help me. Sometimes your mind can hear what's not there, because you think that the singer is singing one thing but she is actually singing something else ("time" versus "dime"). Finally, singers sometimes do sing lyrics that vary from the official written lyrics.