Gasoline is volatile and so is the price. Every day thousands of gas stations across America change their signs showing the cost of gas for the day.
The formula is pretty standard: Sale Price = Wholesale price plus taxes plus profit. At some stations the supplier sets the price. Some stations can set their own price.
Why does it change so often? It’s crude. When crude oil prices change (and they do!), gasoline prices change.
Local stations can set their own prices.