limeex2,
Cambio's are money exchanges. There are several around town. I have always used the FX Trader at the HiLo but there is one on the beach road, I think it's in front of Bourbon Beach and at least one on One Love Drive (the cliff road). I'm sure others will chime in with more.
Rounding up to 100 to 1 actually de-values the Jamaican dollar not the other way around.