Final answer:
When rounding to the nearest cent, you round up if the digit in the thousandths place is 5 or above, and round down if the digit is 4 or below. When adding or subtracting numbers with decimals, round the result to the same number of decimal places as the number with the least number of decimal places.
Step-by-step explanation:
When rounding to the nearest cent, you look at the hundredths place of a number. If the digit in the thousandths place is 5 or above, you round up by adding 1 to the hundredths place. If the digit is 4 or below, you round down by keeping the hundredths place as it is. For example, if you need to round $6.375 to the nearest penny, you would round it up to $6.38. When adding or subtracting numbers, round the result to the same number of decimal places as the number with the least number of decimal places.