This is the same as 17.96c. When it’s rounded to the nearest tenth of a cent, it becomes 18.0c because 0.96c is closer to 1 than it is to 0.90. The rule for rounding is that when the hundredths digit is 5 or more we add 1 to the tenths digit, which is 9, so it makes 10 in the tenths, which carries over into the ones.
The answer is $0.180, the zero at the end simply shows that the answer is accurate to a tenth of a cent (a thousandth of a dollar).