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	$215.43	3.289%	$222.5155	$222.52	$222.50	$222.50
Purchase #2	$216.83	6.303%	$230.4968	$230.50	$230.50	$230.50
Purchase #3	$143.82	5.502%	$151.733	$151.73	$151.75	$151.70
Purchase #4	$11.53	8.560%	$12.517	$12.52	$12.50	$12.50
Purchase #5	$45.72	5.136%	$48.0682	$48.07	$48.05	$48.10
Purchase #6	$212.85	9.866%	$233.8498	$233.85	$233.85	$233.80
Purchase #7	$128.37	13.385%	$145.5523	$145.55	$145.55	$145.60
7 purchase totals =	$974.55		$1,044.7326	$1,044.74	$1,044.70	$1,044.70