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	$114.53	11.120%	$127.2657	$127.27	$127.25	$127.30
Purchase #2	$22.39	7.489%	$24.0668	$24.07	$24.05	$24.10
Purchase #3	$100.64	4.204%	$104.8709	$104.87	$104.85	$104.90
Purchase #4	$11.59	8.318%	$12.5541	$12.55	$12.55	$12.60
Purchase #5	$165.32	4.609%	$172.9396	$172.94	$172.95	$172.90
Purchase #6	$166.52	5.361%	$175.4471	$175.45	$175.45	$175.40
Purchase #7	$234.83	6.137%	$249.2415	$249.24	$249.25	$249.20
7 purchase totals =	$815.82		$866.3857	$866.39	$866.35	$866.40