Need a plug in to calculate my employees mileage

So I have an employee who uses her own vehicle for work purposes. So every week she turns in a mileage report that she creates in excel report for every day from the office to various stops in between and returning to the office.

This can add up to a lot of miles and I have to one by one go through and verify the distance between stops. This turns out to be various tedious and we end up sitting down as the miles she recorded end up being way more than was google map shows (I know sometimes it can be off by a few miles depending on the road conditions)

Is there a plugin that can have my employee enter her stops and give me a report on the miles travel between stops?