Petty cash, petty cash box.
Petty cash:
a small amount of money that is kept in an office for making small payments.
Longman Dictionary of Contemporary English.
In News:
"A FINANCE assistant is accused of pocketing more than £1,500 from Smithills School by fiddling
petty cash funds."
The Bolton News.
"Petty cash fails to balance. Patient accounts exist for people you've never met, let alone treated."
Chiropractic Economics.
"They found a woman inside the school who had several stolen items on
her; including cleaning supplies,
petty cash box, a box of change, two
cameras and six packets of socks."
Fox40.com
"He says that he solves five or six cases like this a month and puts the money in the
petty cash box."
Inside Pulse.