La. Stat. tit. 33 § 4160.30
The certificates may be sold by negotiated sale or may be advertised for sale on sealed bids as provided by law. The governing authority may reject any and all bids received as a result of the advertisement, or the city may contract to deliver the certificates to the contractor as hereinafter provided at a price not less than the best bid received at the advertised sale. The governing authority may, by resolution, authorize the mayor to negotiate and deliver the certificates, to collect the purchase price therefor, and to do any and all things necessary and incidental thereto, or may authorize the delivery to the contractor of all or any of the certificates in payment of their contractual obligation covering the improvements. The funds derived from the sale of the certificates shall be expended solely in payment of the costs of the improvements, and shall not be drawn upon for any other purpose.
La. R.S. § 33:4160.30