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	$196.33	5.860%	$207.8349	$207.83	$207.85	$207.80
Purchase #2	$223.66	4.423%	$233.5525	$233.55	$233.55	$233.60
Purchase #3	$37.46	7.434%	$40.2448	$40.24	$40.25	$40.20
Purchase #4	$244.35	3.321%	$252.4649	$252.46	$252.45	$252.50
Purchase #5	$217.46	4.370%	$226.963	$226.96	$226.95	$227.00
Purchase #6	$31.34	10.445%	$34.6135	$34.61	$34.60	$34.60
Purchase #7	$77.54	10.726%	$85.8569	$85.86	$85.85	$85.90
7 purchase totals =	$1,028.14		$1,081.5305	$1,081.51	$1,081.50	$1,081.60