Vb.net 如何将双值舍入？

我的问题是，当我按下bigmacadd按钮和减号按钮时，bigmac可以正常工作。但是当我按下mcdouble add按钮时，我会得到一堆数字。我怎样才能使它显示为小数点后2.50位

Public Class Form1
    Const bigmac As Decimal = 4D
    Const mcdouble As Decimal = 2.25
    Dim tax As Decimal
    Dim price As Decimal
    Dim quantity As Integer
    Dim finaltotal As Decimal

    Private Sub Btnbigmacadd_Click(sender As Object, e As EventArgs) Handles Btnbigmacadd.Click
        quantity = quantity + 1
        txtquan.Text = quantity

        price += bigmac
        txtprice.Text = price

        tax = price * 0.15
        txttax.Text = tax

        finaltotal = price + tax
        txtfinaltotal.Text = finaltotal
    End Sub

    Private Sub btnbigmacminus_Click(sender As Object, e As EventArgs) Handles btnbigmacminus.Click
        quantity = quantity - 1
        txtquan.Text = quantity

        price -= bigmac
        txtprice.Text = price

        tax = price * 0.15
        txttax.Text = tax

        finaltotal = price + tax
        txtfinaltotal.Text = finaltotal
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        quantity = quantity + 1
        txtquan.Text = quantity

        price += mcdouble
        txtprice.Text = price

        tax = price * 0.15
        txttax.Text = tax

        finaltotal = price + tax
        txtfinaltotal.Text = finaltotal
     End Sub
End Class

---

您可以使用

Math.round

方法将

tax

四舍五入到小数点后两位

tax = Math.Round(price * 0.15D, 2)
txttax.Text = tax.ToString()

finaltotal = price + tax
txtfinaltotal.Text = finaltotal.ToString()

如果要在

税务

和

财务总额

中保留额外的小数位，但在文本框中仅显示两位小数位，可以使用

ToString（“N2”）

方法

tax = price * 0.15D
txttax.Text = tax.ToString("N2")

finaltotal = price + tax
txtfinaltotal.Text = finaltotal.ToString("N2")

---

你需要更具体一些，需要自己努力解决问题。这个节目在做什么？您目前获得的输出“一组数字”是什么？你试过做什么？到目前为止你知道些什么？写下一些代码，说你想要2.50，因为输出不是实现这一点的方法。我猜他得到的总数只有2个小数位，比如2.50293。如果是这样，请使用

txtfinaltotal.Text=Format（finaltotal，“#.00”）

0的平均值，将其四舍五入到小数点后两位。另外：在处理货币时，切勿使用

Double

。相反，在处理金钱时（以及其他精度上的微小误差会产生有意义的后果的事情），应该使用

Decimal

类型。这要慢几个数量级，但有时精度更重要，处理货币计算就是其中之一。