Hi there,
There are numerous threads on the forum that already answer this question. Here’s one:
Petty cash for sitters - my experience so far
You are by no means obligated to leave any cash for sitters, and sitters are expected to cover their own travel costs and food, unless otherwise specified/offered by the owner (which is certainly very generous but isn’t usual). It may be helpful to leave some petty cash in case of emergency or if the sitter may have to buy pet or home supplies during the sit, but it’s certainly not an obligation and is really up to you.