保留两位小数的问题，请大家指教

        下边的******及一下有些弄不明白了，在*******处比较的是第三位和第四位至末尾的数字，何解。下边的呢？
private double round1(double CL1, string NUM)//Num为2
        {
            double next6 = 0;
            int num1 = int.Parse(NUM);
            string nexxx = CL1.ToString();
            string[] sArray = nexxx.Split('.');//取小数点后数字            if (sArray.Length > 1)
            {
                if (sArray[1].Length > num1)
                {
                    string next1 = sArray[1].Substring(num1, 1);//如果是保留两位小数，则判断第三位是否为5,5前位小数奇数进,偶数舍。第三位小数
                    string next2 = sArray[1].Substring(num1 - 1, 1);//保留两位小数,5前是否为奇数还是偶数，第二位小数
                    string next3 = sArray[1].Substring(0, num1);//取小数点后两位小数                    int next4 = int.Parse(next2);                    if (int.Parse(next1) == 5)
                    {
                        //如果5后面有数据,就直接进一位,否则判断
                        if (sArray[1].Substring(num1, 1) != sArray[1].Substring(num1))*******
                        {
                            next6 = Math.Round(CL1, num1);
                        }
                        else
                        {
                            if (next4 % 2 == 0)
                            {
                                string next5 = sArray[0] + "." + next3;
                                next6 = double.Parse(next5);
                            }
                            else
                            {
                                next6 = Math.Round(CL1, num1);                            }
                        }
                    }
                    else
                    {
                        next6 = Math.Round(CL1, num1);
                    }
                }
                else
                {
                    next6 = CL1;
                }
            }
            else
            {
                next6 = CL1;
            }            return next6;        }