I use an Excel spreadsheet to track student grades.  Individual assignment grades are stored with the maximum number of decimal places that Excel will accept.  In computing the final letter grade I round any fraction of 0.49 and down to the next lower integer and any fraction of 0.50 and up to the next higher integer.  PLEASE note - 0.01 points can be the difference between one letter grade and the next.  EVERY POINT COUNTS!  Blowing off a low-value assignment may come back to haunt you when the semester is over and you see your final grade (see Extra Credit).