An electronic commerce system includes a broker that enables customers to purchase items from multiple different merchants. A customer anonymously interacts with the merchants to identify items to purchase, and the merchants provide virtual shopping carts including the item and tax information to the broker. The tax information describes tax rates for the item in multiple jurisdictions. The broker determines the jurisdiction applicable to the customer by, for example, determining a shipping address for the customer. The broker uses the tax information and jurisdiction to calculate the taxes to collect for the item. The broker determines the total cost for the transaction, and conducts an electronic commerce transaction for the item with the customer.