A petrol price works out at 3.899 per gallon, but the till charges only to the nearest cent. The final price must therefore be:

1. Money cannot be paid in fractions of a cent. 2. The extra digit has to be resolved one way or the other. 3. The final price is rounded to the nearest cent. _Source: OpenStax Prealgebra 2e, Chapter 5, Decimals._