C#四舍五入方法

///

       /// 四舍五入方法
       /// 描述:适合处理货币计算【正数四舍五入，负数是五舍六入】
       ///

       public static double Round_Deci(double value, int decimals)
       {
           if (decimals < 0)
               decimals = 0;

           if (value < 0)
           {
               return Math.Round(value + 5 / Math.Pow(10, decimals + 1), decimals,MidpointRounding.AwayFromZero);
           }
           else
           {
               return Math.Round(value, decimals,MidpointRounding.AwayFromZero);
           }
       }
       ///

       /// 四舍五入方法
       /// 描述:适合数据统计【正负数都四舍五入】
       ///

       /// 要四舍五入的数
       /// 要保留的小数点后位数
       ///
       public static double Round_Data(double value, int decimals)
       {
           if (decimals < 0)
               decimals = 0;

           if (value >= 0)
           {
               value += 5 * Math.Pow(10, -(decimals + 1));
           }
           else
           {
               value += -5 * Math.Pow(10, -(decimals + 1));
           }
           string str = value.ToString();
           string[] strs = str.Split('.');
           int idot = str.IndexOf('.');

           if (idot == -1)//没有小数点时就直接返回值[如运行Round_Data(1955.50,0)]，避免出错
               return double.Parse(str);
           string prestr = strs[0];
           string poststr = strs[1];
           if (poststr.Length > decimals)
           {
               poststr = str.Substring(idot + 1, decimals);
           }
           string strd = prestr + "." + poststr;
           value = Double.Parse(strd);
           return value;
       }