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	$178.84	9.395%	$195.642	$195.64	$195.65	$195.60
Purchase #2	$186.98	9.162%	$204.1111	$204.11	$204.10	$204.10
Purchase #3	$191.38	6.747%	$204.2924	$204.29	$204.30	$204.30
Purchase #4	$126.47	13.543%	$143.5978	$143.60	$143.60	$143.60
Purchase #5	$143.61	8.246%	$155.4521	$155.45	$155.45	$155.50
Purchase #6	$82.89	3.472%	$85.7679	$85.77	$85.75	$85.80
Purchase #7	$111.76	4.444%	$116.7266	$116.73	$116.75	$116.70
7 purchase totals =	$1,021.93		$1,105.5899	$1,105.59	$1,105.60	$1,105.60