js toFixed()方法不准确的解决方案

这是我的微信小程序开发过程遇到的问题，从网上找来了一段代码，应该是js都通用的。小程序里面只需要先执行下面的方法fixToFixedIssue里的代码，就可以直接用了。经测试大量数据（见下面方法testMyToFixed），打印结果显示此方法准确可行。

onLoad: function (options) {
    this.fixToFixedIssue()
    this.testMyToFixed()
  },

//js自带的Number.toFixed方法处理小数遇到5的时候是错误的！！有时候舍出，有时候舍入！，必须重写！
//必须在当前页面执行，否则作用范围无法覆盖当前页面
//代码来源，https://www.cnblogs.com/gushen/archive/2012/11/20/2778324.html
  fixToFixedIssue: function() {
    Number.prototype.toFixed = 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 + "";
    };
  },

  testMyToFixed: function () {

    let testArray = [0.010, 0.0149,0.015,0.016,0.017,0.019,
                    0.026, 0.029, 0.02111, 0.078, 0.0711,0.0701,
                    0.10, 0.11, 0.145, 0.149, 0.150, 0.151, 0.155, 0.159,
                    1.001, 1.004,1.005, 1.006,1.009, 1.105, 1.104, 1.109,
                    1.6,1.0, 1.423, 1.531, 1.555, 1.504, 1.506, 1.669, 1.998,
                    998, 996, 910,1,12,33,151, 99999,
                    333.01232, 333.09139, 333.93153, 148.898342, 231.09002,
                    231.000002329, 21.98, 67.473, 33.234, 12.982, 12.238, 896.023,
                    99999.99999]

    for (var i = 0; i < testArray.length;  i++) {
        var value = testArray[i];
        console.log(value + "------" + value.toFixed(2))//0,1,2,30等都测试过，结果正确。
    }
  }