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	$87.59	9.618%	$96.0144	$96.01	$96.00	$96.00
Purchase #2	$58.82	5.399%	$61.9957	$62.00	$62.00	$62.00
Purchase #3	$240.43	4.731%	$251.8047	$251.80	$251.80	$251.80
Purchase #4	$145.64	8.545%	$158.0849	$158.08	$158.10	$158.10
Purchase #5	$59.76	11.189%	$66.4465	$66.45	$66.45	$66.40
Purchase #6	$20.27	3.222%	$20.9231	$20.92	$20.90	$20.90
Purchase #7	$11.45	8.553%	$12.4293	$12.43	$12.45	$12.40
7 purchase totals =	$623.96		$667.6986	$667.69	$667.70	$667.60