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	$200.51	4.660%	$209.8538	$209.85	$209.85	$209.90
Purchase #2	$239.88	10.251%	$264.4701	$264.47	$264.45	$264.50
Purchase #3	$126.48	12.763%	$142.6226	$142.62	$142.60	$142.60
Purchase #4	$14.94	4.554%	$15.6204	$15.62	$15.60	$15.60
Purchase #5	$119.28	9.739%	$130.8967	$130.90	$130.90	$130.90
Purchase #6	$130.86	13.172%	$148.0969	$148.10	$148.10	$148.10
Purchase #7	$140.71	6.649%	$150.0658	$150.07	$150.05	$150.10
7 purchase totals =	$972.66		$1,061.6263	$1,061.63	$1,061.55	$1,061.70