Sign Language 10

When I taught Personal Finance as an online class, I would post photos like this as extra credit opportunities during exams. The question would be something like this:
Assume that you went into this store and ordered the following:

• 1) exactly one gallon of Unleaded gasoline and
• 2) a single 2 Liter bottle of Pepsi.

Furthermore, you demanded that they charge you exactly the prices that they were advertising on their sign as shown in the photo. Also assume that they agreed to charge you the exact prices listed on the sign. What is the total amount that they should charge you (regardless of whether you have the ability to pay that exact amount)?

• a) $3.38
• b) $3.39
• c) $3.389
• d) $2.4089
• e) none of the above

Let's just say that I didn't give away very many extra credit points with these things. Almost everyone gets them wrong. Maybe most of my students were the people who worked at these places and put up the goofy signs in the first place. Check the correct answer here.

Also, hasn't the ship pretty much sailed on the whole 9/10ths of a cent for gasoline prices? Maybe that made sense (well, no, not really) back when prices were 35 cents per gallon. But why do we (they?) care about posting the 9/10ths of a cent when the price is two-fifty a gallon? Will they still do it when the price is five bucks a gallon? Ten bucks a gallon? Isn't this totally absurd? And will people ever learn the difference between the cents sign and the dollar sign? Am I takin' crazy pills here?