If you get a civil demand letter in the mail, it does not mean you have to pay. It's over. Banned for a year is all.
The above is general legal and business analysis. It is not "legal advise" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.
Even if you weren't arrested, the police will most probably be notified of this. The fine the Target sends to you in the may, does not need to be paid, as no one can force you to pay anything unless they have a judgment against you. In order for Target to get a judgment against you by taking you to court. I have never seen that done, and then and only then should you pay their Civil Demand.
However, the criminal case is much different. if convicted of the crime of Petty Theft (Shoplifting) you will most likely have to pay a fine to the court. However, you do not want a criminal record.
Feel free to read my guide by following this link, it should give you some more insight. http://www.avvo.com/legal-guides/ugc/petty-theft---what-you-should-and-should-do-and-other-helpful-hints
If you would like a free consultation, please feel free to call me. I would be glad to go over all your options with you.