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	$97.52	8.544%	$105.8521	$105.85	$105.85	$105.90
Purchase #2	$237.39	7.754%	$255.7972	$255.80	$255.80	$255.80
Purchase #3	$28.46	12.509%	$32.0201	$32.02	$32.00	$32.00
Purchase #4	$11.28	7.583%	$12.1354	$12.14	$12.15	$12.10
Purchase #5	$48.39	12.208%	$54.2975	$54.30	$54.30	$54.30
Purchase #6	$155.39	10.851%	$172.2514	$172.25	$172.25	$172.30
Purchase #7	$212.90	11.176%	$236.6937	$236.69	$236.70	$236.70
7 purchase totals =	$791.33		$869.0474	$869.05	$869.05	$869.10