The casino cashier is located in the “cage.” Each casino only has one cage. They have rows like a bank would. You can also set up a credit line here if needed.
If you need change and you are nowhere near the cage, there are change booths usually scattered throughout the casino. They don’t handle chips, and are usually in the machine areas.
There are attendants on the casino floor that can also help you with change. Roaming change attendants are usually seen pushing a cart. Slot attendants are in the middle of a carousel of machines. They have the buckets for holding all your coins. Ask either of these which machine would be the best to play because they are there every day and might know which ones are loose.
Casinos do have a color coding scheme for their chips. The $1 chips will vary. $5 chips are red. $25 chips are green. $100 chips are black. $500 chips are purple. $1000 chips are yellow. The important thing to remember is that while most casinos follow the same color scheme, they do not accept each other’s chips.
Slot machines will also take US denominations of bills to play. Nickel and quarter machines will also take US coins to play. You can only get change at the cages and booths. The attendants will refuse to do it.
A secret that most people don’t know is you can can place cash on the table if it is just for one or two quick bets. For example, at a $2 Blackjack table, you can place two dollar on the table for the minimum bet on each hand. You can’t do it for long, but you should be able to play two or three hands. So if you are on your way out the door, you can still make a last minute bet.