datagridview AllowUserToAddRows new row not add

I want to add a single row to the datagridview. According to the data I entered on the line I added, the calculations specified in the class should be made. When I say add a new line, I want a new line to appear and calculations on the same class.

the first row insertion and calculation process is taking place. 
but when I want to add a second line, the new line is not created. 
I am sharing my sample codes with you. Please your support.

public MyDesktop()
{
InitializeComponent();
bindingSource1.DataSource = typeof(TEST);

dataGridView1.AutoGenerateColumns = false;
dataGridView1.DataSource = bindingSource1;
dataGridView1.ToolClick += DataGridView1_ToolClick;

}

private void DataGridView1_ToolClick(object sender, ToolClickEventArgs e)
{
dataGridView1.AllowUserToAddRows = true;
dataGridView1.BeginEdit();
dataGridView1.SetValue(QUANTITY, dataGridView1.NewRowIndex, 1);
dataGridView1.SetValue(PRICE, dataGridView1.NewRowIndex, 1);
dataGridView1.EndEdit();
dataGridView1.AllowUserToAddRows = false;
}

public class TEST
{
public float _QUANTITY { get; set; }
public float QUANTITY {
get { return _QUANTITY; }
set {
_QUANTITY = value;
TOTAL_PRICE = value * PRICE; }
}
public float _PRICE { get; set; }
public float PRICE {
get { return _PRICE; }
set {
_PRICE = value;
TOTAL_PRICE = PRICE * value; }
}
public float TOTAL_PRICE { get; set; }

}