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	$195.78	9.376%	$214.1363	$214.14	$214.15	$214.10
Purchase #2	$126.31	12.447%	$142.0318	$142.03	$142.05	$142.00
Purchase #3	$34.37	11.801%	$38.426	$38.43	$38.45	$38.40
Purchase #4	$196.55	6.763%	$209.8427	$209.84	$209.85	$209.80
Purchase #5	$231.53	4.600%	$242.1804	$242.18	$242.20	$242.20
Purchase #6	$72.89	6.692%	$77.7678	$77.77	$77.75	$77.80
Purchase #7	$145.89	3.546%	$151.0633	$151.06	$151.05	$151.10
7 purchase totals =	$1,003.32		$1,075.4483	$1,075.45	$1,075.50	$1,075.40