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	$76.74	11.845%	$85.8299	$85.83	$85.85	$85.80
Purchase #2	$29.74	7.188%	$31.8777	$31.88	$31.90	$31.90
Purchase #3	$73.91	4.164%	$76.9876	$76.99	$77.00	$77.00
Purchase #4	$72.30	8.641%	$78.5474	$78.55	$78.55	$78.50
Purchase #5	$133.53	11.457%	$148.8285	$148.83	$148.85	$148.80
Purchase #6	$161.68	6.697%	$172.5077	$172.51	$172.50	$172.50
Purchase #7	$184.55	12.353%	$207.3475	$207.35	$207.35	$207.30
7 purchase totals =	$732.45		$801.9263	$801.94	$802.00	$801.80