js JS 浮点计算BUG

Number.prototype.toRound = function(d)
{
var s=this+"";if(!d)d=0;
if(s.indexOf(".")==-1)s+=".";s+=new Array(d+1).join("0");
if (new RegExp("^(-|\+)?(\d+(\.\d{0,"+ (d+1) +"})?)\d*$").test(s))
{
var s="0"+ RegExp.$2, pm=RegExp.$1, a=RegExp.$3.length, b=true;
if (a==d+2){a=s.match(/d/g); if (parseInt(a[a.length-1])>4)
{
for(var i=a.length-2; i>=0; i--) {a[i] = parseInt(a[i])+1;
if(a[i]==10){a[i]=0; b=i!=1;} else break;}
}
s=a.join("").replace(new RegExp("(\d+)(\d{"+d+"})\d$"),"$1.$2");
}if(b)s=s.substr(1);return (pm+s).replace(/.$/, "");} return this+"";
};

var result = (i+0.1+0.1).toRound(2);