Does it work for gas at a tenth of a penny?
It doesn’t seem to be able to influence a consumer’s decision to buy gas at a particular station, because every station does it. That is, when comparing $1.879 and $1.889, there is still one penny difference, just as if it had been $1.88 and $1.89.
It doesn’t seem to be able to influence the decision of the quantity of gas to buy: people buy gas in one of three ways: (1) they fill their tank, (2) they buy a certain dollar amount, or (3) they buy a certain number of gallons.
If (1), then they received a slight discount on the gas bill because of the merchant’s decision to knock a tenth of a cent off per gallon.
If (2), then they spent the same amount and drove away with less gas.
If (3), then they again received a small discount on the price of gas for X gallons.
The only marketing effect that’s left is some effect on whether to buy gas or not (or whether to drive somewhere or not, spurring the demand for gas). If that’s it, then is a penny itself too small to make much of a difference? Unless consumer behavior varies with a penny increase or decrease, it will not vary with an illusory 9/10 of a penny decrease (especially not a permanent one that happened before we were even born).