/// <summary>
/// Check if string is all numerals
/// If not reset value to '00'
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TextboxValueCheck(object sender, TextChangedEventArgs e)
{
TextBox txt = (TextBox)sender;
if (!HelperMethods.AreAllValidNumericChars(txt.Text))
{
txt.Text = "00";
txt.CaretIndex = txt.Text.Length;
}
}