/// <summary>
 /// Get total sum including any VAT
 /// </summary>
 /// <param name="subscription"></param>
 /// <returns></returns>
 public static Decimal?GetTotalSum(this StripeSubscription subscription)
 {
     return(subscription.GetSubTotal() + subscription.GetVatSum());
 }
 /// <summary>
 /// Get vat sum
 /// </summary>
 /// <param name="subscription"></param>
 /// <returns></returns>
 public static Decimal?GetVatSum(this StripeSubscription subscription)
 {
     return(subscription.GetSubTotal() * ((subscription.TaxPercent ?? 0) / 100m));
 }