What is the Spanish equivalent of "petty cash"?
Petty cash is relatively small amounts of money kept on hand for unforeseeen expenses at home or at a place of business.
Cómo Usar Una Caja Chica En Su Pequeña Empresa
Contabilizando Y Controlando Los Gastos Menores
That sounds like accounting to me and here is the link!
That's from the dictionary on this site. So I don't know if it's right.
I'm an accountant and that's something I should know!
Efectivo para gastos menores --- right off the translator
I also found caja chica
You can say feria or morralla, both means small amount of money in coins.
If you mean savings, you can say guardadito or ahorritos.
Check this link.