Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$196.83	4.222%	$205.1402	$205.14	$205.15	$205.10
Purchase #2	$13.56	7.734%	$14.6087	$14.61	$14.60	$14.60
Purchase #3	$167.42	13.848%	$190.6043	$190.60	$190.60	$190.60
Purchase #4	$47.56	8.355%	$51.5336	$51.53	$51.55	$51.50
Purchase #5	$139.83	5.302%	$147.2438	$147.24	$147.25	$147.20
Purchase #6	$246.38	5.395%	$259.6722	$259.67	$259.65	$259.70
Purchase #7	$166.30	12.680%	$187.3868	$187.39	$187.40	$187.40
7 purchase totals =	$977.88		$1,056.1896	$1,056.18	$1,056.20	$1,056.10