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	$214.61	7.322%	$230.3237	$230.32	$230.30	$230.30
Purchase #2	$16.87	10.344%	$18.615	$18.62	$18.60	$18.60
Purchase #3	$190.54	11.160%	$211.8043	$211.80	$211.80	$211.80
Purchase #4	$189.79	3.482%	$196.3985	$196.40	$196.40	$196.40
Purchase #5	$124.68	5.555%	$131.606	$131.61	$131.60	$131.60
Purchase #6	$84.57	10.103%	$93.1141	$93.11	$93.10	$93.10
Purchase #7	$198.41	12.247%	$222.7093	$222.71	$222.70	$222.70
7 purchase totals =	$1,019.47		$1,104.5709	$1,104.57	$1,104.50	$1,104.50