Rounding Column Footer in Datatables

Question

In column 17 I have taken total[1] and divided it by total[0]. The number is a long decimal. How would I shorten that decimal so that the value in column 17 to only have three decimal places (rounding to the nearest thousandths place if it has more than 3 decimals)

$(document).ready(function() {
  $('#battingtbl').DataTable({
    "searching": true,
    "pageLength": 40,
    "scrollX": true,
    "paging": false,
    "info": false,
    drawCallback: () => {
      const table = $('#battingtbl').DataTable();
      const tableData = table.rows({
        search: 'applied'
      }).data().toArray();
      const totals = tableData.reduce((total, rowData) => {
        total[0] += parseFloat(rowData[6]);
        total[1] += parseFloat(rowData[8]);
        return total;
      }, [0, 0]);
      $(table.column(6).footer()).text(totals[0]);
      $(table.column(8).footer()).text(totals[1]);
      $(table.column(17).footer()).text(totals[1] / totals[0]); // I WANT TO ROUND THIS
    }
  })
});