$189.47 is actually the correct answer, because e1 ($37.89) is really
37.894. Do this with a calculator and see.

Although Excel hid the .004 from you when you formatted it to show the
dollar sign, it kept it, and multiplied it by a1 (5), hence the 2 cents
difference.

To "fix" this, you could have to apply ROUND to steps e1 and f1
(anywhere that you multiply or divide).