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	$196.40	4.820%	$205.8665	$205.87	$205.85	$205.90
Purchase #2	$26.31	4.157%	$27.4037	$27.40	$27.40	$27.40
Purchase #3	$16.83	4.634%	$17.6099	$17.61	$17.60	$17.60
Purchase #4	$107.63	3.405%	$111.2948	$111.29	$111.30	$111.30
Purchase #5	$204.52	7.142%	$219.1268	$219.13	$219.15	$219.10
Purchase #6	$179.98	8.275%	$194.8733	$194.87	$194.85	$194.90
Purchase #7	$94.99	11.345%	$105.7666	$105.77	$105.75	$105.80
7 purchase totals =	$826.66		$881.9416	$881.94	$881.90	$882.00