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	$184.89	8.677%	$200.9329	$200.93	$200.95	$200.90
Purchase #2	$48.61	8.762%	$52.8692	$52.87	$52.85	$52.90
Purchase #3	$180.34	6.406%	$191.8926	$191.89	$191.90	$191.90
Purchase #4	$162.36	6.227%	$172.4702	$172.47	$172.45	$172.50
Purchase #5	$126.64	12.270%	$142.1787	$142.18	$142.20	$142.20
Purchase #6	$208.79	12.153%	$234.1642	$234.16	$234.15	$234.20
Purchase #7	$47.71	5.829%	$50.491	$50.49	$50.50	$50.50
7 purchase totals =	$959.34		$1,044.9988	$1,044.99	$1,045.00	$1,045.10