My husband kindly downloaded a handy-dandy app on to my phone, which would do a great job tracking mileage... if I could only remember to either turn it on or off when heading out for business. Inevitably I forget one or the other.
So when it comes to tax time I often have to resort to other methods to figure out my business kms.
One trick, is that anytime I have a business receipt for a store or a bank deposit, I know that I can claim the kms traveled to and from that location. For example, Staples is approximately 3 kms from my office. I can claim 6 kms for every Staples receipt I have, and the expenses for the office supplies I purchased, while I was at it. My receipts are now pulling double duty! :)