Greenbacks rhymes with:
greenback's, greenback's, greenback's, greenback's, buybacks, comebacks, cutbacks, drawbacks, flashbacks, fullbacks, givebacks, greenback's, halfbacks, kickbacks, leasebacks, leatherbacks, paperbacks, paybacks, pricklebacks, pullbacks, quarterbacks, razorback's, razorbacks, rollbacks, setbacks
Greenbacks sounds like:
greenback, greenback's, greenbush, greenpeace, greenpeace's, grownups