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	$199.89	7.561%	$215.0037	$215.00	$215.00	$215.00
Purchase #2	$236.96	5.826%	$250.7653	$250.77	$250.75	$250.80
Purchase #3	$194.76	6.209%	$206.8526	$206.85	$206.85	$206.90
Purchase #4	$12.47	3.837%	$12.9485	$12.95	$12.95	$12.90
Purchase #5	$41.99	11.659%	$46.8856	$46.89	$46.90	$46.90
Purchase #6	$9.64	7.835%	$10.3953	$10.40	$10.40	$10.40
Purchase #7	$185.45	3.142%	$191.2768	$191.28	$191.30	$191.30
7 purchase totals =	$881.16		$934.1278	$934.14	$934.15	$934.20