Any account holder receiving rights to purchase stock in the subscription offering may also receive, without payment, nontransferable subscription rights to purchase up to one percent of the total offering of shares of capital stock, to the extent that the shares are available after satisfying the subscription under RCW 32.32.045 and 32.32.055, subject to such conditions as may be provided in the plan of conversion. In the event of an oversubscription for the additional shares, the shares available shall be allocated among the subscribing eligible account holders and supplemental eligible account holders on such equitable basis, related to the amounts of their respective subscriptions, as may be provided in the plan of conversion. Where possible the subscriptions shall be allocated in such a manner that total purchases by eligible account holders and supplemental eligible account holders shall be rounded to the nearest one hundred shares.