For repair work we charge an extra half hour on each service call for travel time and pay the service tech an extra half hour's pay on each job.
(1/4 hour to get to each job and 1/4 hour to get back.)
In other words for the first 1/2 hour (or less) the customer is charge for one hour minimum.
After the first 1/2 hour we break it down by each additional quarter hour on the job.
It all averages out in the long run because the service tech might get paid 1/2 hour to get to his next job which is actually 5 minutes away or might be 45 minutes away.
Sometimes he can actually get 10 or more hours pay for an 8 hour day.
It works for us because we stay in a fairly small area and seldom drive very far.
Lately we have been adding $10.00 to each job or $10.00 per day on two day or more jobs for Gasoline.