When selling products or services online, choosing the right e-commerce shopping cart software is a critical decision. Shopping cart software allows customers to shop online and add products and service to the cart so they can make a purchase. When a customer checks out, the shopping cart software calculates order total, shipping and handling costs, and any taxes that may be levied. Since so many calculations are built into the software code, it is critical the e-commerce provider has appropriate controls around system development and change management. If the shopping cart calculates totals improperly, it can have a direct impact on the financials of the online retailer. In addition to SSAE 16 requirements, e-commerce providers need to ensure their software is PCI compliant, as they will be liable for any non-compliance issues.