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	$202.98	10.102%	$223.485	$223.49	$223.50	$223.50
Purchase #2	$75.59	13.719%	$85.9602	$85.96	$85.95	$86.00
Purchase #3	$149.65	13.500%	$169.8528	$169.85	$169.85	$169.90
Purchase #4	$116.87	12.831%	$131.8656	$131.87	$131.85	$131.90
Purchase #5	$239.64	4.327%	$250.0092	$250.01	$250.00	$250.00
Purchase #6	$144.26	5.243%	$151.8236	$151.82	$151.80	$151.80
Purchase #7	$49.45	9.473%	$54.1344	$54.13	$54.15	$54.10
7 purchase totals =	$978.44		$1,067.1308	$1,067.13	$1,067.10	$1,067.20