1. The county commission, at noon on or before the first Monday of July for the year in which a bid is requested and every second or fourth year thereafter, shall publicly open the bids, and cause each bid to be entered upon the records of the commission, and shall select as the depositaries of all the public funds of every kind and description going into the hands of the county treasurer, and also all the public funds of every kind and description going into the hands of the collector-treasurer in counties under township organization, the deposit of which is not otherwise provided for by law, the banking corporations or associations whose bids respectively made for one or more of the parts of the funds shall in the aggregate constitute the largest offer for the payment of interest per annum for the funds; but the commission may reject any and all bids.

2. The interest upon each fund shall be computed upon the daily balances with the depositary, and shall be payable to the county treasurer monthly, who shall place the interest to the credit of each individual fund held by the county treasurer; provided, that the interest on any funds collected by the collector of any county of the first classification not having a charter form of government on behalf of any political subdivision or special district shall be credited to such political subdivision or special district.

3. The county clerk shall, in opening the bids, return the certified checks deposited with him to the banks whose bids are rejected, and on approval of the security of the successful bidders return the certified checks to the banks whose bids are accepted.