Do vending machines take pennies? I have never yet heard a candy machine I purchased food from that took mine.
As far as pennies go, it is a time consumer and when the idiot in front of you has no shame but to use them without any regard to the fact they are holding up traffic and being childish and irresponsible. Then when I work the lanes you have people give them to you not even counting it and then you have to count it all to only find out that they are short a big difference where they have to have you (and the queue) wait while they dig for more pennies to be short even some more is most annoying not to mention unbelievable.
I even had one guy hand me a $100 bill once right after another person broke a $ 100 bill as well. That was rare that two back to back patrons had such large bills, but I just started my shift where the first car took most of my change. Believe it or not this second individual was going to wait until I called a second party to open the safe indoors inside the plaza office and get him his money and stage a sit in even if the queue behind him piles up over a mile long. I had to pursuade him after the driver and his antagonizing girlfriend were ranting that the plaza has money from all the motorists passing through the lanes constantly, to take a mail in slip and pay the stupid toll.
Anyway point is, there is no rules governing this kind of behavior, and its sad that the Parkway did not mean what they said with the sign on the booths about pennies as it allows such assholes to be irresponsible while driving. Yes it should be known that as much as pennies are part of the system for payment of debts, yes many of us consider it inappropriate.
I did hear though that among the silly laws that are out there like displaying our American flag on the left side of a room or mainly to the right of the stage looking out, courtroom Bench from the judge, or Altar from the minister's ambo there is one too that really state's that being prejudice about penny use is illegal too. I do not know about that, but if the flag issue can make it, so can this as well.