All bonds issued under this chapter shall be direct and general obligations of the unit issuing the same, for the payment of which the full faith and credit of the unit shall be irrevocably pledged. In each fiscal year while any funding or refunding bonds issued under this chapter shall be outstanding, there shall be levied upon all taxable property in the unit an ad valorem tax sufficient to pay the interest thereon as it falls due and the principal of such bonds which shall then have matured or which shall mature within the same fiscal year, and any sinking fund payments which may be provided for by the bonds or by the resolution authorizing the same, as well as all deficits in such interest, principal and sinking fund payments arising from failure to comply with this chapter or by failure to collect the taxes levied or otherwise; provided, that the governing body, in its discretion, may levy in any fiscal year a tax sufficient to pay, in addition to the interest and principal which shall fall due in such fiscal year, any portion of the interest or principal which shall fall due in any succeeding fiscal year, and may also levy in any fiscal year a tax for sinking fund payments in addition to the tax required for such payments by the resolution authorizing any of such bonds. The governing body may provide in the resolution authorizing the issuance of any such funding or refunding bonds that any sinking fund provided for such bonds shall be used solely for the purpose of redemption of the bonds authorized by such resolution, and all bonds so purchased or redeemed shall be cancelled and shall not be reissued.