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	$54.77	13.585%	$62.2105	$62.21	$62.20	$62.20
Purchase #2	$165.44	6.678%	$176.4881	$176.49	$176.50	$176.50
Purchase #3	$25.89	13.264%	$29.324	$29.32	$29.30	$29.30
Purchase #4	$56.49	7.666%	$60.8205	$60.82	$60.80	$60.80
Purchase #5	$118.32	7.397%	$127.0721	$127.07	$127.05	$127.10
Purchase #6	$94.65	5.510%	$99.8652	$99.87	$99.85	$99.90
Purchase #7	$211.53	7.536%	$227.4709	$227.47	$227.45	$227.50
7 purchase totals =	$727.09		$783.2513	$783.25	$783.15	$783.30