§ 625. Undertaking on appeal. No appeal shall be taken by an employer from a decision of the appeal board determining a sum to be due from such employer unless the amount involved, with interest and penalties thereon, if any, shall be first deposited with the commissioner and an undertaking filed with the commissioner, in such amount and with such sureties as a justice of the supreme court shall approve, to the effect that the employer will pay all costs and charges which may be adjudged against him in the prosecution of such appeal. At the option of the employer, such undertaking may be in a sum sufficient to cover the said amount, interest, penalties, costs, and charges as aforesaid, in which event the employer shall not be required to deposit such amount, with the interest and penalties, as a condition precedent to the taking of an appeal.