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	$57.77	3.389%	$59.7278	$59.73	$59.75	$59.70
Purchase #2	$238.42	10.613%	$263.7235	$263.72	$263.70	$263.70
Purchase #3	$210.43	7.133%	$225.44	$225.44	$225.45	$225.40
Purchase #4	$70.82	8.482%	$76.827	$76.83	$76.85	$76.80
Purchase #5	$42.53	4.433%	$44.4154	$44.42	$44.40	$44.40
Purchase #6	$128.49	6.778%	$137.1991	$137.20	$137.20	$137.20
Purchase #7	$245.57	3.669%	$254.58	$254.58	$254.60	$254.60
7 purchase totals =	$994.03		$1,061.9128	$1,061.92	$1,061.95	$1,061.80