Battling to overcome deepening losses, the board of Jackson Health System wants voters to approve a new taxing district that might add $300 a year in taxes to the average Miami homeowner. Jackson's leaders have been struggling to find new revenue because of the rising numbers of uninsured and lower funds from the sales and property tax money it already receives. The system faced a $133 million shortfall in 2010 before it balanced its budget by announcing the closure of nursing homes and primary care centers.