asp.net数据四舍五入

#region 数据四舍五入  
/// <summary>  
/// 四舍五入  
/// </summary>  
/// <param name="dblnum">源数据</param>  
/// <param name="numberprecision">小数位</param>  
/// <returns></returns>  
private double GetRound(object objnum, int numberprecision)  
{  
    double returnnum = 0;  
    if (objnum != null)  
    {  
        try  
        {  
            double dblnum = double.Parse(objnum.ToString());  
            int tmpNum = dblnum > 0 ? 5 : -5;  
            double dblreturn = Math.Truncate(dblnum * Math.Pow(10, numberprecision + 1)) + tmpNum;  
            dblreturn = Math.Truncate(dblreturn / 10) / Math.Pow(10, numberprecision);  
            returnnum = dblreturn;  
        }  
        catch { }  
    }  
    return returnnum;  
}  
#endregion