What I would like to do is to have Goal seek give me the closest number, to
the true answer, down to the penny. If the correct answer is 99.995859694 -
the answer should be 100.

Can I tell goal seek to stop once the input changes by less than a penny?

If the answer is to change the options-calculation-maximum iterations and
maximum change. My follow up question is what other features of Excel do
these two items control?