We tend to make decisions like this all the time, without thinking too much about why we make them. In this instance, the thought processes are unconscious, but they probably go something like this:
"It might cost me four or five dollars, but if it's a work trip I might get a tax deduction for the toll. I don't really like being in tunnels, but at least I won't get snarled up on Sandgate Road, so stuff it, I'll pay the five bucks and probably get to where I'm headed quicker".
In other words, think carefully before trying to pick up pennies in front of a steamroller.
And we're usually quite good at updating a hypothesis as more information comes to light. Inevitably, we sometimes make mistakes, though.