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	$230.46	11.542%	$257.0597	$257.06	$257.05	$257.10
Purchase #2	$14.41	3.270%	$14.8812	$14.88	$14.90	$14.90
Purchase #3	$59.47	9.733%	$65.2582	$65.26	$65.25	$65.30
Purchase #4	$106.85	4.152%	$111.2864	$111.29	$111.30	$111.30
Purchase #5	$248.66	3.321%	$256.918	$256.92	$256.90	$256.90
Purchase #6	$154.61	6.769%	$165.0756	$165.08	$165.10	$165.10
Purchase #7	$200.71	5.870%	$212.4917	$212.49	$212.50	$212.50
7 purchase totals =	$1,015.17		$1,082.9708	$1,082.98	$1,083.00	$1,083.10