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	$200.93	10.779%	$222.5882	$222.59	$222.60	$222.60
Purchase #2	$25.38	11.363%	$28.2639	$28.26	$28.25	$28.30
Purchase #3	$29.99	11.863%	$33.5477	$33.55	$33.55	$33.50
Purchase #4	$17.39	5.517%	$18.3494	$18.35	$18.35	$18.30
Purchase #5	$180.28	11.212%	$200.493	$200.49	$200.50	$200.50
Purchase #6	$46.29	3.813%	$48.055	$48.06	$48.05	$48.10
Purchase #7	$60.45	3.737%	$62.709	$62.71	$62.70	$62.70
7 purchase totals =	$560.71		$614.0062	$614.01	$614.00	$614.00