As part of the federal government’s escalating efforts to shut down the medical marijuana industry, the IRS is claiming that Harborside Health Center, an Oakland dispensary that is thought by many to represent the best practices in the industry, owes them roughly $2.5 million in back taxes. The reason for this is that during the audit, the IRS would not let Harborside deduct many of its business expenses. Most of these expenses were for things that all other legitimate businesses are allowed to deduct,…