How important is that last 20 minutes of charging?

My commute to work happens to be about 25 miles, so I can usually do fully EV if I charge at work. I usually make a stop on the way back, close to home, where I can plug in to 120V for an hour or two, so I need even less energy to get back.

Charging at work is not free though, 50 cents an hour - so around over $1.10 to fully charge. And gas for 25 miles at 60 MPG (my experience) is around $1.25, so the EV charging is very close to the Not Worth It price.
(I was cut off from just plugging into the 120V outlets )

So, because I'm paying by the minute, and the car starts charging very slowly at the end, is it ok to just only charge it to the point that the power draw goes down and skip those last few miles of range? Is it doing some kind of battery conditioning or something that isn't ok to only do once per day?