No manual intervention needed just track everything and retain the data for a long time. Then you can query the database for all serial numbers your target has ever taken out of an ATM and where they where returned. Circulation will diffuse these results somewhat but that follows a normal distribution. That means it is much more likely that a bill that was spent at a store by your target which is given out again as change, is more likely to be spent at another store near that original store. Aggregate this information over a couple of weeks or months and you will get a heatmap of locations to check out. You can run this operation automatically on all bank accounts if you want. Threshold the heatmap at some significant value and you get a list of stores visited by each person with X% probability.