53 Pa. C.S. § 8166
In the case of public sale, bid security shall be given by each bidder, shall be in cash or by certified or official bank check payable to the local government unit and shall be not less than 2% of the principal amount of the bonds or notes to be purchased. The bid security of the unsuccessful bidder or bidders shall be returned to each unsuccessful bidder, without interest, in accordance with written instructions of the bidder conforming to the official notice of sale, promptly upon an award of the bonds or notes or upon the rejection of all bids. The bid security of the successful bidder shall be retained by the treasurer of the local government unit and, with or without allowance for interest as the official notice of sale may specify, shall be applied on the purchase price when the bonds or notes are actually delivered and paid for, retained as liquidated damages if the bidder defaults, or returned to the bidder with interest at the judgment rate if, after an acceptance of the proposal, the bonds or notes are not issued for any reason not constituting a default by the bidder. Unless required by the local governing body, no bid security shall be required in the case of tax anticipation notes, bond anticipation notes or notes to be issued under section 8109 (relating to small borrowing for capital purposes).
53 Pa.C.S. § 8166