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	$133.25	11.109%	$148.0527	$148.05	$148.05	$148.10
Purchase #2	$166.74	11.796%	$186.4087	$186.41	$186.40	$186.40
Purchase #3	$117.86	4.247%	$122.8655	$122.87	$122.85	$122.90
Purchase #4	$51.64	3.154%	$53.2687	$53.27	$53.25	$53.30
Purchase #5	$120.54	5.674%	$127.3794	$127.38	$127.40	$127.40
Purchase #6	$26.34	4.863%	$27.6209	$27.62	$27.60	$27.60
Purchase #7	$148.41	7.454%	$159.4725	$159.47	$159.45	$159.50
7 purchase totals =	$764.78		$825.0684	$825.07	$825.00	$825.20