The finance director shall strictly enforce the provisions of the budget. The finance director shall not authorize any payment or the incurring of any obligation by the City unless an appropriation has been made in the budget resolution and there are sufficient unexpended funds left after deducting the total past expenditures and encumbrances against the appropriation. No officer or employee of the City shall place any order to make any purchase except for a purpose and to the amount authorized in the budget resolution. No check shall be issued or transfer made to any account other than one owned by the City until the claim to which it relates has been supported by an itemized bill, payroll, or time sheet or other document approved and signed by the responsible city officer who vouches for its correctness and reasonableness.