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	$196.92	13.694%	$223.8862	$223.89	$223.90	$223.90
Purchase #2	$164.25	4.568%	$171.7529	$171.75	$171.75	$171.80
Purchase #3	$126.67	11.536%	$141.2827	$141.28	$141.30	$141.30
Purchase #4	$150.35	8.613%	$163.2996	$163.30	$163.30	$163.30
Purchase #5	$158.72	4.525%	$165.9021	$165.90	$165.90	$165.90
Purchase #6	$103.50	7.845%	$111.6196	$111.62	$111.60	$111.60
Purchase #7	$205.46	12.293%	$230.7172	$230.72	$230.70	$230.70
7 purchase totals =	$1,105.87		$1,208.4603	$1,208.46	$1,208.45	$1,208.50