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	$118.26	7.675%	$127.3365	$127.34	$127.35	$127.30
Purchase #2	$213.89	5.449%	$225.5449	$225.54	$225.55	$225.50
Purchase #3	$163.83	5.153%	$172.2722	$172.27	$172.25	$172.30
Purchase #4	$243.27	3.726%	$252.3342	$252.33	$252.35	$252.30
Purchase #5	$151.87	8.435%	$164.6802	$164.68	$164.70	$164.70
Purchase #6	$228.46	5.847%	$241.8181	$241.82	$241.80	$241.80
Purchase #7	$249.63	10.510%	$275.8661	$275.87	$275.85	$275.90
7 purchase totals =	$1,369.21		$1,459.8522	$1,459.85	$1,459.85	$1,459.80