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	$196.88	10.516%	$217.5839	$217.58	$217.60	$217.60
Purchase #2	$216.71	10.514%	$239.4949	$239.49	$239.50	$239.50
Purchase #3	$214.41	4.452%	$223.9555	$223.96	$223.95	$224.00
Purchase #4	$44.27	12.696%	$49.8905	$49.89	$49.90	$49.90
Purchase #5	$100.45	3.247%	$103.7116	$103.71	$103.70	$103.70
Purchase #6	$142.95	6.592%	$152.3733	$152.37	$152.35	$152.40
Purchase #7	$152.96	8.783%	$166.3945	$166.39	$166.40	$166.40
7 purchase totals =	$1,068.63		$1,153.4042	$1,153.39	$1,153.40	$1,153.50