Here's a
trip calculator that you can use to figure out the toll cost for Illinois. In Illinois tolls are double for those without a transponder.
Are you open to a route change? If you go through Milwaukee I would recommend I-294 (Tri-State Tollway) and go around Chicago.
If you go through Madison you have 3 options.
1. I-39 to I-80 Extra hour or so, much cheaper on tolls, best for traffic
2. I-90 to I-290 to I-355 to I-80 Extra 15-20 minutes when compared to option 3. Roads are tolls but pretty good. Better traffic than I-294
3. I-90 to I-290 to I-294 to I-80
Chicago traffic can be bad at any time of day. I would avoid the city unless you're going through in the middle of the night. Even then there can be lane closures.
In general, the farther out from the city the better the traffic. Google Maps is your friend.