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	$161.52	3.773%	$167.6141	$167.61	$167.60	$167.60
Purchase #2	$84.89	5.282%	$89.3739	$89.37	$89.35	$89.40
Purchase #3	$158.73	10.391%	$175.2236	$175.22	$175.20	$175.20
Purchase #4	$139.82	4.195%	$145.6854	$145.69	$145.70	$145.70
Purchase #5	$104.92	8.678%	$114.025	$114.03	$114.05	$114.00
Purchase #6	$234.27	10.509%	$258.8894	$258.89	$258.90	$258.90
Purchase #7	$200.59	8.349%	$217.3373	$217.34	$217.35	$217.30
7 purchase totals =	$1,084.74		$1,168.1487	$1,168.15	$1,168.15	$1,168.10