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	$101.49	10.767%	$112.4174	$112.42	$112.40	$112.40
Purchase #2	$192.56	11.370%	$214.4541	$214.45	$214.45	$214.50
Purchase #3	$156.93	10.747%	$173.7953	$173.80	$173.80	$173.80
Purchase #4	$174.32	9.158%	$190.2842	$190.28	$190.30	$190.30
Purchase #5	$45.66	6.699%	$48.7188	$48.72	$48.70	$48.70
Purchase #6	$212.40	5.528%	$224.1415	$224.14	$224.15	$224.10
Purchase #7	$96.50	3.194%	$99.5822	$99.58	$99.60	$99.60
7 purchase totals =	$979.86		$1,063.3935	$1,063.39	$1,063.40	$1,063.40