$.07. You do not write $.7 because that would mean 70 cents and should be written with a 0 at the end anyways. You do not write any dollar amount with a cents sign at the end, because the dollar sign replaces it. You write $.07 because 7 cents means 7/100 (7 one hundredths) so the seven must be written in the hundredths spot. Remember, the hundredth spot is the second number after a decimal.
