China Petrochemical's fuel card is round every time it is refueled. Why are there numbers after the decimal point?

In order to calculate the price accurately. Refueling will be rounded off because the oil gun at the gas station is automatically calibrated according to the whole liter of each refueling, not according to the actual refueling amount. After refueling, the oil gun will automatically stop refueling, rounded to the nearest whole liter. Rounded figures and figures after decimal point left by the actual fuel quantity are used to accurately calculate the price. China Petrochemical Co., Ltd., referred to as "China Petrochemical" or "China Petrochemical", is a super-large petrochemical enterprise group reorganized by the state on the basis of the former sinopec group in July 2008.