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	$60.63	3.684%	$62.8636	$62.86	$62.85	$62.90
Purchase #2	$38.64	12.334%	$43.4059	$43.41	$43.40	$43.40
Purchase #3	$72.35	6.548%	$77.0875	$77.09	$77.10	$77.10
Purchase #4	$43.29	8.159%	$46.822	$46.82	$46.80	$46.80
Purchase #5	$31.32	4.751%	$32.808	$32.81	$32.80	$32.80
Purchase #6	$184.64	13.125%	$208.874	$208.87	$208.85	$208.90
Purchase #7	$141.30	9.195%	$154.2925	$154.29	$154.30	$154.30
7 purchase totals =	$572.17		$626.1535	$626.15	$626.10	$626.20