It depends on precisely what you mean by this question.
If the fine that you are talking about was imposed by the court, after you went to court and pleaded or were found guilty, it was probably part of a sentence that included a suspended jail sentence and a term of probation of some sort. If the fine arose in that setting, your failure to pay it will result in a finding that you are not in compliance with the terms of your probation and you may be subject to being incarcerated.
If the fine you are talking about is just the "civil penalty" imposed by Walmart for shoplifting, your failure to pay it will have the same consequence as your failure to pay any other debt. You will be sued for it, you will likely be charged attorneys fees for the lawsuit and there will likely then be an increase in the fee and ultimately a judgment against you for the money. It is also possible that Walmart, if they didnt move forward with prosecuting your criminally for the shoplifting in the first place, might decide to do so if you don't pay the fine. That will not likely result in any problems for your visa.
You should speak with counsel about the situation to make sure you understand all of the consequences and have described all of the facts.