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	$57.78	11.104%	$64.1959	$64.20	$64.20	$64.20
Purchase #2	$160.42	7.808%	$172.9456	$172.95	$172.95	$172.90
Purchase #3	$71.28	3.146%	$73.5225	$73.52	$73.50	$73.50
Purchase #4	$198.68	12.563%	$223.6402	$223.64	$223.65	$223.60
Purchase #5	$53.78	12.354%	$60.424	$60.42	$60.40	$60.40
Purchase #6	$241.85	4.827%	$253.5241	$253.52	$253.50	$253.50
Purchase #7	$175.60	8.552%	$190.6173	$190.62	$190.60	$190.60
7 purchase totals =	$959.39		$1,038.8696	$1,038.87	$1,038.80	$1,038.70