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	$235.76	11.391%	$262.6154	$262.62	$262.60	$262.60
Purchase #2	$53.90	12.420%	$60.5944	$60.59	$60.60	$60.60
Purchase #3	$161.90	6.766%	$172.8542	$172.85	$172.85	$172.90
Purchase #4	$52.87	10.718%	$58.5366	$58.54	$58.55	$58.50
Purchase #5	$172.69	10.383%	$190.6204	$190.62	$190.60	$190.60
Purchase #6	$183.27	12.310%	$205.8305	$205.83	$205.85	$205.80
Purchase #7	$163.91	5.806%	$173.4266	$173.43	$173.45	$173.40
7 purchase totals =	$1,024.30		$1,124.4781	$1,124.48	$1,124.50	$1,124.40