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	$44.30	5.471%	$46.7237	$46.72	$46.70	$46.70
Purchase #2	$66.91	8.529%	$72.6168	$72.62	$72.60	$72.60
Purchase #3	$53.83	10.667%	$59.572	$59.57	$59.55	$59.60
Purchase #4	$48.52	11.243%	$53.9751	$53.98	$54.00	$54.00
Purchase #5	$118.89	10.606%	$131.4995	$131.50	$131.50	$131.50
Purchase #6	$245.69	12.206%	$275.6789	$275.68	$275.70	$275.70
Purchase #7	$229.29	3.144%	$236.4989	$236.50	$236.50	$236.50
7 purchase totals =	$807.43		$876.5649	$876.57	$876.55	$876.60