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	$155.78	11.663%	$173.9486	$173.95	$173.95	$173.90
Purchase #2	$160.96	10.685%	$178.1586	$178.16	$178.15	$178.20
Purchase #3	$51.84	11.823%	$57.969	$57.97	$57.95	$58.00
Purchase #4	$111.95	6.778%	$119.538	$119.54	$119.55	$119.50
Purchase #5	$98.72	10.156%	$108.746	$108.75	$108.75	$108.70
Purchase #6	$100.60	10.616%	$111.2797	$111.28	$111.30	$111.30
Purchase #7	$152.52	9.246%	$166.622	$166.62	$166.60	$166.60
7 purchase totals =	$832.37		$916.2619	$916.27	$916.25	$916.20