What to do about a very small discrepancy between bookkeeping and bank acc?

Hi all,

at the end of the last FY my books (QB) showed a balance of USD4.27 (foreign currency acc), but the bank account was USD0.00 (correct). I have tried to find the error, but there are so many transaction that I can't make out the cause. Might be due to currency conversion related things.

What may I (legally!) do in order to bring the books down to USD0.00?

Thank you in advance.