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	$184.92	9.140%	$201.8217	$201.82	$201.80	$201.80
Purchase #2	$26.85	8.509%	$29.1347	$29.13	$29.15	$29.10
Purchase #3	$108.93	6.746%	$116.2784	$116.28	$116.30	$116.30
Purchase #4	$194.73	4.440%	$203.376	$203.38	$203.40	$203.40
Purchase #5	$163.39	5.594%	$172.53	$172.53	$172.55	$172.50
Purchase #6	$182.39	7.534%	$196.1313	$196.13	$196.15	$196.10
Purchase #7	$94.57	6.418%	$100.6395	$100.64	$100.65	$100.60
7 purchase totals =	$955.78		$1,019.9116	$1,019.91	$1,020.00	$1,019.80