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	$179.72	9.122%	$196.1141	$196.11	$196.10	$196.10
Purchase #2	$13.81	13.244%	$15.639	$15.64	$15.65	$15.60
Purchase #3	$101.71	12.131%	$114.0484	$114.05	$114.05	$114.00
Purchase #4	$240.86	12.857%	$271.8274	$271.83	$271.85	$271.80
Purchase #5	$167.52	10.323%	$184.8131	$184.81	$184.80	$184.80
Purchase #6	$134.28	13.659%	$152.6213	$152.62	$152.60	$152.60
Purchase #7	$12.30	5.283%	$12.9498	$12.95	$12.95	$12.90
7 purchase totals =	$850.20		$948.0131	$948.01	$948.00	$947.80