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	$151.28	6.643%	$161.3295	$161.33	$161.35	$161.30
Purchase #2	$157.89	9.160%	$172.3527	$172.35	$172.35	$172.40
Purchase #3	$148.30	4.316%	$154.7006	$154.70	$154.70	$154.70
Purchase #4	$67.72	13.540%	$76.8893	$76.89	$76.90	$76.90
Purchase #5	$194.98	11.107%	$216.6364	$216.64	$216.65	$216.60
Purchase #6	$71.44	6.447%	$76.0457	$76.05	$76.05	$76.00
Purchase #7	$148.85	6.206%	$158.0876	$158.09	$158.10	$158.10
7 purchase totals =	$940.46		$1,016.0418	$1,016.05	$1,016.10	$1,016.00