The locations I am using are from a third party database.  I am not sure by what criteria are the exact coordinates of counties chosen.  In most cases, the coordinates of counties appears to be close to the county seat.  For some reason, the coordinates for Monroe County were 11 miles north of town, about a mile into Lake Erie.  I just edited the coordinates to be the same ones as for Rochester itself.  So you and every other business with a Rochester address is listed as 0 miles away. 

The database I am using is not an address database, so unfortunately I am not able to distinguish between a business in Rochester that is right next to the courthouse and a business with a Rochester address that is 10 miles away.  That may not be perfectly fair or accurate in that a business that is actually 10 miles away from the Monroe County Courthouse gets credit for being 0 miles away but I think it is fair enough, and as a practical matter it is the best I can do given the data that is freely available to me in the form of a database of a size that I can use.  All businesses within Rochester, or any other city, are now ordered randomly on each search, so you and your Rochester competitors with free listings will each rotate randomly to the top of the list. 

A note to all regarding how cities and counties are located, generally: 

If you are puzzled by the mileage that is being shown from your business to a particular county, there is a way to see why that is.  Go to http://www.geonames.org website, and type in the name of your city or county, i.e. "Rochester, NY" or "Monroe County, NY".   A list will come up of place names.  Click on your place name in the list.  A Google Maps map will appear with the location of the coordinates for your place name.  If your city or county place name appears in an odd location, let me know, I will correct it within reason.