The latest release of X-Cart (version 4.5.0) comes with TaxCloud already built-in. This means that you won’t need to install a separate module to use TaxCloud. Just install X-Cart and configure TaxCloud from the admin console and you will have the most accurate and easy to use tax rate calculation service available.
More information is available on the X-Cart website.
Posted by Dave 
TaxCloud Developer Blog 