The routing for dispatches is provided by PC Miler - practical miles. There is no way to offer options for routing. Sometimes the routing doesn't match what the driver actually traveled. The best way to solve this problem is to add an extra dispatch point to effect the routing.
Example: Pick up a load in Me and deliver in IL - PC Miler will route you through Canada - try adding an extra shipper in Buffalo - this will force the routing to stay on the U.S. side.