route to vpn based on destination
The problem is that normal routing tables use IP addresses, while you're trying to make the decision based on the domain name. I don't believe there is anything built into Windows that can do what you want. Perhaps, if you're just trying to access web pages, try setting up a proxy which will send traffic out the VPN tunnel and then configure your browser to only use the proxy for certain addresses (.com in this instance), and then the rest go out your normal default gateway.