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	$212.85	9.354%	$232.76	$232.76	$232.75	$232.80
Purchase #2	$148.86	11.287%	$165.6618	$165.66	$165.65	$165.70
Purchase #3	$86.60	5.243%	$91.1404	$91.14	$91.15	$91.10
Purchase #4	$198.37	12.698%	$223.559	$223.56	$223.55	$223.60
Purchase #5	$161.80	6.724%	$172.6794	$172.68	$172.70	$172.70
Purchase #6	$19.60	12.288%	$22.0084	$22.01	$22.00	$22.00
Purchase #7	$103.93	4.651%	$108.7638	$108.76	$108.75	$108.80
7 purchase totals =	$932.01		$1,016.5728	$1,016.57	$1,016.55	$1,016.70