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	$208.49	3.116%	$214.9865	$214.99	$215.00	$215.00
Purchase #2	$55.82	12.107%	$62.5781	$62.58	$62.60	$62.60
Purchase #3	$62.88	6.214%	$66.7874	$66.79	$66.80	$66.80
Purchase #4	$87.38	13.665%	$99.3205	$99.32	$99.30	$99.30
Purchase #5	$125.48	4.621%	$131.2784	$131.28	$131.30	$131.30
Purchase #6	$68.71	3.766%	$71.2976	$71.30	$71.30	$71.30
Purchase #7	$89.41	3.733%	$92.7477	$92.75	$92.75	$92.70
7 purchase totals =	$698.17		$738.9962	$739.01	$739.05	$739.00