Betsy says "Don't Trust that Nine-Tenths of a Cent at Your Gas Station."
As we all guessed, when you buy a gallon of gas, you're not paying in fractions of a penny. They're actually rounding up. And there is no good reason to advertise their prices that way except to fool people into thinking that gas is actually a penny less than it really is.
This is one of the oldest techniques in the marketing playbook; that why many retail prices are set at levels such as $5.99, $49.99 or $399.99…to get people to think that prices are lower than they actually are.
Why would gas be any different?