Here is the format for Excel's ROUND function:
=ROUND(expression, decimal places)
The expression argument is usually a formula that generates the value that is to be rounded off. The second argument, decimal places, specifies the number of decimal places to which the value generated by the expression will be rounded.
The formula for the periodic interest in cell C14 is "B14*B$5" and we want to round this value to two decimal places (the nearest penny):
=ROUND(expression, decimal places)
=ROUND(B14*B$5, 2)