Green’s Dictionary of Slang

1. (US) insignificant.

2000		G. Pelecanos Shame the Devil 102: Lonnie Newton was a small-change coke dealer who had experienced a run of good luck in the past six months.
2005		M.B. ‘Chopper’ Read Chopper 4 183: Trevor ‘small-change’ Pettingill will want to pray to God that it wasn’t his fault that the calabrian got pinched.

2. (US prison) used of a prisoner who is almost at the end of their sentesmall-change adj. (2)nce.

2010

L. Berney Gutshot Straight [ebook] ‘That right, Shake? [...] You’re small change?’ ‘Walks outta here a free man in seventy-two hours’.