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	$227.68	8.868%	$247.8707	$247.87	$247.85	$247.90
Purchase #2	$65.98	6.783%	$70.4554	$70.46	$70.45	$70.50
Purchase #3	$28.81	7.443%	$30.9543	$30.95	$30.95	$31.00
Purchase #4	$212.70	4.733%	$222.7671	$222.77	$222.75	$222.80
Purchase #5	$144.80	7.852%	$156.1697	$156.17	$156.15	$156.20
Purchase #6	$27.81	5.426%	$29.319	$29.32	$29.30	$29.30
Purchase #7	$241.53	5.830%	$255.6112	$255.61	$255.60	$255.60
7 purchase totals =	$949.31		$1,013.1474	$1,013.15	$1,013.05	$1,013.30