Função multiplicação float por 100 erro java script

  // Closure
//Acredito que proteje o escopo global do javascript para alterar o objeto estatico Math
(function(){
	
	/**
	 * Decimal adjustment of a number.
	 *
	 * @param		type	The type of adjustment.
	 * @param		value	The number.
	 * @param		exp		The exponent (the 10 logarithm of the adjustment base).
	 * @returns				The adjusted value.
	 */
	function decimalAdjust(type, value, exp) {
		// If the exp is undefined or zero...
		if (typeof exp === 'undefined' || +exp === 0) {
			return Math[type](value);
		}
		value = +value;
		exp = +exp;
		// If the value is not a number or the exp is not an integer...
		if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) {
			return NaN;
		}
		// Shift
		value = value.toString().split('e');
		value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp)));
		// Shift back
		value = value.toString().split('e');
		return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp));
	}

	// Decimal round
	if (!Math.round10) {
		Math.round10 = function(value, exp) {
			return decimalAdjust('round', value, exp);
		};
	}
	// Decimal floor
	if (!Math.floor10) {
		Math.floor10 = function(value, exp) {
			return decimalAdjust('floor', value, exp);
		};
	}
	// Decimal ceil
	if (!Math.ceil10) {
		Math.ceil10 = function(value, exp) {
			return decimalAdjust('ceil', value, exp);
		};
	}
})();

 function multiplica() { 
  var s = document.forms[0];
  var valor20 = parseFloat(s.km.value.replace('.','').replace(',','.'));
  var valor21 = (1.15); 
  var valor30 =('' + ((valor20||0) * (valor21||0)));
  valor30 = Math.round10(valor30, -2).toFixed(2);
  s.seis.value = fmtMoney(valor30);
}

//TESTES DE VALIDAÇÃO USANDO A NORMALIZAÇÃO DO MOZILLA DEVELOPERS
contaTeste1 = 1 * 1.15;
contaTeste2 = 10 * 1.15;
contaTeste3 = 100 * 1.15; 
alert("teste1: " + Math.round10(contaTeste1, -2).toFixed(2));
alert("teste2: " + Math.round10(contaTeste2, -2).toFixed(2));
alert("teste3: " + Math.round10(contaTeste3, -2).toFixed(2));