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	$46.60	3.316%	$48.1453	$48.15	$48.15	$48.10
Purchase #2	$62.57	5.289%	$65.8793	$65.88	$65.90	$65.90
Purchase #3	$13.88	13.596%	$15.7671	$15.77	$15.75	$15.80
Purchase #4	$68.56	4.542%	$71.674	$71.67	$71.65	$71.70
Purchase #5	$226.84	12.729%	$255.7145	$255.71	$255.70	$255.70
Purchase #6	$51.28	7.725%	$55.2414	$55.24	$55.25	$55.20
Purchase #7	$53.41	5.826%	$56.5217	$56.52	$56.50	$56.50
7 purchase totals =	$523.14		$568.9433	$568.94	$568.90	$568.90