What is an alternate way to write this code

' Local variable declarations
        Dim dblLengthOfStay As Double           ' To hold the number of days in the hospital
        Dim dblMedicationCharges As Double      ' To hold the medication charges
        Dim dblSurgicalCharges As Double        ' To hold the surgical charges
        Dim dblLabFees As Double                ' To hold the lab fees
        Dim dblPhysicalRehabCharges As Double   ' To hold the physical rehabilitation charges
        Dim dblStayCharges As Double            ' To hold the base charges for the hospital stay
        Dim dblMiscCharges As Double            ' To hold the total of miscelaneous charges
        Dim dblTotalCharges As Double           ' To hold the total charges

        ' Get the length of stay as input from the user.
        ' Verify that the value is a positive real number.
        If Double.TryParse(txtLengthOfStay.Text, dblLengthOfStay) And
            dblLengthOfStay >= 0.0 Then

            ' Get the medication charges as input from the user.
            ' Verify that the value is a positive real number.
            If Double.TryParse(txtMedicationCharges.Text, dblMedicationCharges) And
                dblMedicationCharges >= 0.0 Then

                ' Get the surgical charges as input from the user.
                ' Verify that the value is a positive real number.
                If Double.TryParse(txtSurgicalCharges.Text, dblSurgicalCharges) And
                    dblSurgicalCharges >= 0.0 Then

                    ' Get the lab fees as input from the user.
                    ' Verify that the value is a positive real number.
                    If Double.TryParse(txtLabFees.Text, dblLabFees) And
                        dblLabFees >= 0.0 Then

                        ' Get the physical rehabilitation charges as input from the user.
                        ' Verify that the value is a positive real number.
                        If Double.TryParse(txtPhysicalRehabCharges.Text, dblPhysicalRehabCharges) And
                            dblPhysicalRehabCharges >= 0.0 Then

                            ' Call the CalcStayCharges function and store the result.
                            dblStayCharges = CalcStayCharges(dblLengthOfStay, dblCHARGE_PER_DAY)

                            ' Call the CalcMiscCharges function and store the result.
                            dblMiscCharges = CalcMiscCharges(dblMedicationCharges, dblSurgicalCharges,
                                                             dblLabFees, dblPhysicalRehabCharges)

                            ' Call the CalcTotalCharges function and store the result.
                            dblTotalCharges = CalcTotalCharges(dblStayCharges, dblMiscCharges)

                            ' Display the total charges as output to the user.
                            lblTotalCharges.Text = dblTotalCharges.ToString("c")
                        Else
                            ' Display a message to the user indicating that the value for the physical
                            ' rehabilitation charges is invalid.
                            MessageBox.Show("The physical rehabilitation charges must " &
                                            "be a positive real number.", "Invalid Input")
                        End If
                    Else
                        ' Display a message to the user indicating that the value for the lab fees is invalid.
                        MessageBox.Show("The lab fees must be a positive real number.", "Invalid Input")
                    End If
                Else
                    ' Display a message to the user indicating that the value for the surgical charges is invalid.
                    MessageBox.Show("The surgical charges must be a positive real number.", "Invalid Input")
                End If
            Else
                ' Display a message to the user indicating that the value for the medication charges is invalid.
                MessageBox.Show("The medication charges must be a positive real number.", "Invalid Input")
            End If
        Else
            ' Display a message to the user indicating that the value for the length of stay is invalid.
            MessageBox.Show("The length of stay must be a positive real number.", "Invalid Input")
        End If
    End Sub