Jason is correct. Round means just that, it rounds things.

Notice the difference.

Round(22 / 7, 4) = 3.1429
Round(22 / 7, 10) = 3.1428571429

the 8571429 is ROUNDed up to 9.

Format will not, as the number of decimal places is explicitly set. In other words, Format is a...formatting function. Round is a....mathematical function.

Which to use is a matter of requirements. Which do you need?