Note: This post applies to U.S. based merchants only. Nearly every U.S.-based product seller is going to have a sales tax due date in January. Some sellers have to file sales tax often and have the whole sales tax thing licked. But many only have to file sales tax once per year. For those sellers, January and it's many sales tax due dates can be a cold and unwelcome wake up call after the fun and profitable holiday season. But never fear, the sales tax compliance process can be broken down...