c# 保留2位小数 整数时无小数

  /// <summary>
        /// 金额
        /// </summary>
        public decimal tax_amount { get; set; }
        /// <summary>
        /// 如是整数，则直接显示整数
        /// </summary>
        public string tax_amountFormat {
            get { return tax_amount.ToString("0.##"); }
              
         }
        /// <summary>
        /// 如是整数，则后面会有两位小娄，如2.00
        /// </summary>
        public string tax_amountFormat2
        {
            get { return tax_amount.ToString("0.00"); }

        }
        /// <summary>
        /// 如是整数，则后面会有两位小娄，如2.00
        /// </summary>
        public string tax_amountFormat3
        {
            get { return tax_amount.ToString("f2"); }

        }