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	$214.41	7.768%	$231.0654	$231.07	$231.05	$231.10
Purchase #2	$229.67	11.292%	$255.6043	$255.60	$255.60	$255.60
Purchase #3	$177.94	12.218%	$199.6807	$199.68	$199.70	$199.70
Purchase #4	$101.60	4.814%	$106.491	$106.49	$106.50	$106.50
Purchase #5	$101.92	3.487%	$105.474	$105.47	$105.45	$105.50
Purchase #6	$182.92	4.714%	$191.5428	$191.54	$191.55	$191.50
Purchase #7	$62.71	4.296%	$65.404	$65.40	$65.40	$65.40
7 purchase totals =	$1,071.17		$1,155.2622	$1,155.25	$1,155.25	$1,155.30