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	$142.42	8.602%	$154.671	$154.67	$154.65	$154.70
Purchase #2	$62.51	6.518%	$66.5844	$66.58	$66.60	$66.60
Purchase #3	$106.47	9.616%	$116.7082	$116.71	$116.70	$116.70
Purchase #4	$120.63	5.616%	$127.4046	$127.40	$127.40	$127.40
Purchase #5	$240.37	4.325%	$250.766	$250.77	$250.75	$250.80
Purchase #6	$249.53	10.305%	$275.2441	$275.24	$275.25	$275.20
Purchase #7	$153.85	13.494%	$174.6105	$174.61	$174.60	$174.60
7 purchase totals =	$1,075.78		$1,165.9888	$1,165.98	$1,165.95	$1,166.00