Most of the bigger companies pay loaded and unloaded miles, but pay Rand McNally miles where they kind of screw you because they figure the mileage by the shortest route, not the actual route you have to take. Some companies like Roehl pay practical miles where they actually figure in truck routes and bypasses around cities, and a very few pay actual hub miles, the actual miles you traveled.
Dot Foods, by the way, pays hub miles.