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	$80.84	13.805%	$92	$92.00	$92.00	$92.00
Purchase #2	$56.54	10.503%	$62.4784	$62.48	$62.50	$62.50
Purchase #3	$52.84	12.182%	$59.277	$59.28	$59.30	$59.30
Purchase #4	$166.95	7.114%	$178.8268	$178.83	$178.85	$178.80
Purchase #5	$32.84	4.463%	$34.3056	$34.31	$34.30	$34.30
Purchase #6	$154.68	11.592%	$172.6105	$172.61	$172.60	$172.60
Purchase #7	$123.27	3.431%	$127.4994	$127.50	$127.50	$127.50
7 purchase totals =	$667.96		$726.9977	$727.01	$727.05	$727.00