are the tolls in colorado cash or cashless?

Cashless, at least the ones I've encountered around Denver.

They photo your license plate and bill you.

I'm assuming you're a visitor - will you have a rental car? If so, you'll want to check the surcharge added by rental car agencies.

CO doesn't have many toll roads...yet.

We were there a few years ago, it was a bit creepy: The toll off ramps were closed, yet we received a bill in the mail. This was north of Denver. Didn't know that technology existed. Hopefully no one is picking their nose.

Rental car tolls get right on up--$25

Hertz charges a convenience fee of $5.95 for PlatePass charges on their cars.

All tolls and that includes non-separated toll lanes and express lanes are license photo only. A toll responder/electronic toll does receive a discount. The license plate toll is the most expensive.

PS You can pick your nose. They do not take a picture of the driver. Just the license plate. The traffic violation cameras take your picture.