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	$10.25	6.729%	$10.9397	$10.94	$10.95	$10.90
Purchase #2	$122.25	9.817%	$134.2513	$134.25	$134.25	$134.30
Purchase #3	$238.37	7.574%	$256.4241	$256.42	$256.40	$256.40
Purchase #4	$233.83	4.508%	$244.3711	$244.37	$244.35	$244.40
Purchase #5	$44.45	8.863%	$48.3896	$48.39	$48.40	$48.40
Purchase #6	$187.32	6.452%	$199.4059	$199.41	$199.40	$199.40
Purchase #7	$250.82	3.111%	$258.623	$258.62	$258.60	$258.60
7 purchase totals =	$1,087.29		$1,152.4047	$1,152.40	$1,152.35	$1,152.40