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	$194.72	11.777%	$217.6522	$217.65	$217.65	$217.70
Purchase #2	$200.28	12.616%	$225.5473	$225.55	$225.55	$225.50
Purchase #3	$97.46	13.483%	$110.6005	$110.60	$110.60	$110.60
Purchase #4	$122.27	4.215%	$127.4237	$127.42	$127.40	$127.40
Purchase #5	$214.72	3.114%	$221.4064	$221.41	$221.40	$221.40
Purchase #6	$86.54	5.732%	$91.5005	$91.50	$91.50	$91.50
Purchase #7	$162.63	6.623%	$173.401	$173.40	$173.40	$173.40
7 purchase totals =	$1,078.62		$1,167.5316	$1,167.53	$1,167.50	$1,167.50