Not sure about your market, but indicating a "travel charge" would not go over well in mine.
I roll-up any extraordinary travel costs into my quote as part of the entire service.
In most cases, traveling greater than 5 miles is simply the cost of doing business.
I usually consider a distance greater than ~30 miles to be where I add an expense for time and greater overhead.
You need to ask yourself, "What's my time worth? Do I pass on expenses related to travel over 5 miles to each customer?"
BTW, the IRS reimbursement for employee travel is ~$0.50 per mile.