In all cases of work to be done by contract, or of the purchase of chattels of any kind, where the amount involved is more than Two Thousand Five Hundred Dollars, unless the council shall by an emergency ordinance otherwise provided, the council shall advertise for bids in such manner as may be designated by the council. Contracts of this magnitude shall be let only by the council to the lowest responsible bidder. The council may, however, reject any and all bids. Nothing contained in this section shall prevent the council from contracting for the doing of work with patented processes, or from the purchasing of patented appliances. Subject to the provisions of this charter, the council may by ordinance adopt further regulations for the making of bids and the letting of contracts. All contracts shall be let to the lowest responsible bidder. The “lowest responsible bidder” shall be interpreted as giving the council the right to accept any bid which it determines is most advantageous to the City.