回复：Do you have some money to find

I agree this idea: correct/prepare material/information that can help you explain why you did not take that big amount of money from store (based on every day's transaction), by the way, if they want to prove you steal that big amount, they need prove they did let you handle that big amount first(It's kind hard to believe a little store can let only one person handle that big amount of transaction).
Also you should prepare something to support you thought that you plan to put those money back to store after go through your financial difficulty. And say you regret you did that, and ask their forgive.

Do not worry, it should not be a big deal, maybe you will be fined to pay them back more money, or may let you do some service for public for few days. I beilieve the sued side may just want get some money back. It does not benefit them to let you go into jail.
(Since this is not like the case to hurt people).
You need tell this to your parents to get their understand especially if you need financial help from them, or emothional support.
Your life is really precious, do not feel desperate.
I support you.