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	$103.26	10.492%	$114.094	$114.09	$114.10	$114.10
Purchase #2	$160.31	4.189%	$167.0254	$167.03	$167.05	$167.00
Purchase #3	$74.62	4.828%	$78.2227	$78.22	$78.20	$78.20
Purchase #4	$88.66	13.653%	$100.7647	$100.76	$100.75	$100.80
Purchase #5	$236.92	8.138%	$256.2005	$256.20	$256.20	$256.20
Purchase #6	$226.27	5.850%	$239.5068	$239.51	$239.50	$239.50
Purchase #7	$159.43	5.259%	$167.8144	$167.81	$167.80	$167.80
7 purchase totals =	$1,049.47		$1,123.6285	$1,123.62	$1,123.60	$1,123.60