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	$181.70	7.780%	$195.8363	$195.84	$195.85	$195.80
Purchase #2	$86.40	3.397%	$89.335	$89.34	$89.35	$89.30
Purchase #3	$45.69	5.291%	$48.1075	$48.11	$48.10	$48.10
Purchase #4	$37.63	10.495%	$41.5793	$41.58	$41.60	$41.60
Purchase #5	$115.66	9.176%	$126.273	$126.27	$126.25	$126.30
Purchase #6	$106.43	4.782%	$111.5195	$111.52	$111.50	$111.50
Purchase #7	$133.83	7.230%	$143.5059	$143.51	$143.50	$143.50
7 purchase totals =	$707.34		$756.1565	$756.17	$756.15	$756.10