I should follow up on this post and let everyone know what happened.
I didn't completely decide on how to handle my exiting of I-88 until while we were on the road. I knew I'd be spending several dollars on tolls along I-88 (both heading toward Dubuque and heading back home), so I opted to pay as few tolls as possible everywhere else. We took I-80/94 west (the Borman and Kingery Expressways) to I-94 west (the Bishop Ford) to I-90/94 (the Dan Ryan) to I-290 west to the beginning (eastern terminus) of I-88. We could have taken either the the Tri-State to eastbound I-88 (to get those easternmost 2 miles and turn around), but my goal was to pay zero in tolls until arriving at I-88.
We ran into some heavy traffic approaching downtown Chicago on the Dan Ryan, but once we got onto I-290 west it was a breeze.
It's funny. I had come prepared with a whole bunch of change in case I needed it. It turns out that every toll booth we drove through had a live person who could have given me exact change if I needed it. The reason we only went through the manned toll booths was because, Friday night, I took I-88 all the way to I-39 and backtracked east into DeKalb via IL 38. Then Saturday morning, we took IL 38 west back to I-39.
Saturday afternoon I only paid one toll along I-88 eastbound (somewhere before I-39). That was also a manned toll booth.