Carrying a fair bit of low denomination change, 1,2 dollar bills etc... is advised as it's a big tipping culture and tipping is expected - even being told when it's not enough! Best to have the change available to give than risk not getting anything back.
Tipping should be taken into account in all restaurants, bars, taxis etc... as well.
We were lucky in finding an lovely bartender in a bar we had a drink in waiting for check in, she ran us through how much was expected for each thing, e.g. a dollar a drink (alcohol in a bar), 15% minimum taxi fare etc... but that was a fair few years ago now so not sure what is currently expected. I found bills in some eating places would be rounded up and not to expect change back as it's assumed it's a tip.
We had a taxi fare confirmed to us pre-ride by the taxi marshalls at Newark airport (then add on tolls for coming in etc...). We gave what we thought was quite a generous tip and was told quite bluntly it wasn't enough!