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	$217.56	4.516%	$227.385	$227.39	$227.40	$227.40
Purchase #2	$9.63	11.743%	$10.7609	$10.76	$10.75	$10.80
Purchase #3	$51.38	6.709%	$54.8271	$54.83	$54.85	$54.80
Purchase #4	$40.93	10.537%	$45.2428	$45.24	$45.25	$45.20
Purchase #5	$10.81	12.371%	$12.1473	$12.15	$12.15	$12.10
Purchase #6	$160.31	4.229%	$167.0895	$167.09	$167.10	$167.10
Purchase #7	$209.49	4.630%	$219.1894	$219.19	$219.20	$219.20
7 purchase totals =	$700.11		$736.6420	$736.65	$736.70	$736.60