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	$200.92	3.871%	$208.6976	$208.70	$208.70	$208.70
Purchase #2	$15.60	12.254%	$17.5116	$17.51	$17.50	$17.50
Purchase #3	$47.59	7.133%	$50.9846	$50.98	$51.00	$51.00
Purchase #4	$104.84	3.143%	$108.1351	$108.14	$108.15	$108.10
Purchase #5	$194.90	8.483%	$211.4334	$211.43	$211.45	$211.40
Purchase #6	$247.58	4.721%	$259.2683	$259.27	$259.25	$259.30
Purchase #7	$105.46	5.603%	$111.3689	$111.37	$111.35	$111.40
7 purchase totals =	$916.89		$967.3995	$967.40	$967.40	$967.40