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I'm sorry to hear about your situation. Yes, it's possible that they could press charges (it's the prosecutor that "files charges"). But if they don't do it then, it's unlikely that they do it later. Generally they want the police to come by and charge you right away. The fact is that this is attempted petty theft. An attempted crime is charged at a lesser amount than the actual crime itself, so in other words it'd be "petty petty theft". The point is that they probably feel that pressing charges (where they'd have to complete paperwork, go to court to testify, etc... ) wouldn't be worth the effort given the small nature, and rather the threat of going after you would be more persuasive.
So frankly I wouldn't worry too much about it.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable.
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Thank you, ***** ***** luck to you!