Usually not for a first offense like this. You may get diverted or probation; either way you should be able to avoid jail.
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You're unlikely to go to jail but you should hire an attorney as soon as possible. If you hire an attorney he can attempt to convince the DA not file this case or if a filing occurs to divert the matter to keep a clean record.
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This is nothing to panic about nobody can predict whether you will be going to jail or not. However, most likely you are eligible for a program called diversion which would require you to do some theft classes pay some fines and possibly do some community service work and your case would be dismissed. If it is dismissed pursuant to this program you can legally say in response to any employment questions that you have never been arrested or convicted of a crime. So get on the phone and you should look for a bay area criminal attorney who can assist in this matter.