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	$58.66	11.802%	$65.5831	$65.58	$65.60	$65.60
Purchase #2	$219.47	13.586%	$249.2872	$249.29	$249.30	$249.30
Purchase #3	$11.43	12.823%	$12.8957	$12.90	$12.90	$12.90
Purchase #4	$73.49	13.486%	$83.4009	$83.40	$83.40	$83.40
Purchase #5	$165.44	4.478%	$172.8484	$172.85	$172.85	$172.80
Purchase #6	$248.29	4.679%	$259.9075	$259.91	$259.90	$259.90
Purchase #7	$196.61	10.507%	$217.2678	$217.27	$217.25	$217.30
7 purchase totals =	$973.39		$1,061.1906	$1,061.20	$1,061.20	$1,061.20