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	$63.54	11.696%	$70.9716	$70.97	$70.95	$71.00
Purchase #2	$153.39	12.397%	$172.4058	$172.41	$172.40	$172.40
Purchase #3	$79.72	12.363%	$89.5758	$89.58	$89.60	$89.60
Purchase #4	$12.35	8.192%	$13.3617	$13.36	$13.35	$13.40
Purchase #5	$207.97	12.168%	$233.2758	$233.28	$233.30	$233.30
Purchase #6	$108.27	8.667%	$117.6538	$117.65	$117.65	$117.70
Purchase #7	$199.29	9.186%	$217.5968	$217.60	$217.60	$217.60
7 purchase totals =	$824.53		$914.8413	$914.85	$914.85	$915.00