My trip is not to the non-profit and back home. I am a pet taxi. I drive to the non-profit animal shelter from home and pick up a pet. I then drive that pet to the vet/animal hospital and then drive back home. Sometimes its the reverse, I drive from home to the vet/animal hospital and pickup a pet that had been fixed. Then drive that pet to the non-profit animal shelter and then drive home. Do I get to deduct the entire round trip or just the distance between the non-profit shelter and the vet performing the service?