A century or so ago, John D. Rockefeller's Standard Oil Company held a virtual monopoly in the American petroleum industry. It was he who devised that little 9/10 cent tacked onto the posted price of his gasoline.
He knew that people have a left digit bias, a psychological quirk exploited by sellers adding nines to prices of goods to disguise real costs. Rockefeller made billions with his extra fraction of a cent. Rockefeller's innovation was a gift that has not died with him.
We usually ignore that 9/1 0 of a cent per litre. What is a fraction of a cent? Well, when added price per gallon it was less than when we are paying by the litre. That small addition per litre amounts to an extra four cents per gallon. Suddenly that looks like real money every time we fill the tank.
It is time for Rockefeller's trick to die so prices become more honest, even if still in lock step through corporate collusion.