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	$149.48	9.365%	$163.4788	$163.48	$163.50	$163.50
Purchase #2	$46.63	4.390%	$48.6771	$48.68	$48.70	$48.70
Purchase #3	$49.96	5.618%	$52.7668	$52.77	$52.75	$52.80
Purchase #4	$167.93	13.703%	$190.9414	$190.94	$190.95	$190.90
Purchase #5	$117.51	8.176%	$127.1176	$127.12	$127.10	$127.10
Purchase #6	$173.80	13.105%	$196.5765	$196.58	$196.60	$196.60
Purchase #7	$214.70	8.728%	$233.439	$233.44	$233.45	$233.40
7 purchase totals =	$920.01		$1,012.9972	$1,013.01	$1,013.05	$1,013.00