主题：四舍五入

        For Each dr As DataRow In DataTables("缴款书").DataRows
            Dim s1 As String = "字符日期 = '" & s & "'"
            dr("头数") = DataTables("销售").Compute("Sum(份数)",s1)
            dr("重量") = DataTables("销售").Compute("Sum(重量)",s1)
            dr("金额") = DataTables("销售").Compute("Sum(金额)",s1)
            round2(dr("金额"),2)
        Next
为什么四舍五入不起作用？