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	$76.96	11.661%	$85.9343	$85.93	$85.95	$85.90
Purchase #2	$171.98	7.249%	$184.4468	$184.45	$184.45	$184.40
Purchase #3	$129.85	6.396%	$138.1552	$138.16	$138.15	$138.20
Purchase #4	$79.32	4.425%	$82.8299	$82.83	$82.85	$82.80
Purchase #5	$188.78	13.500%	$214.2653	$214.27	$214.25	$214.30
Purchase #6	$204.84	11.599%	$228.5994	$228.60	$228.60	$228.60
Purchase #7	$111.86	13.663%	$127.1434	$127.14	$127.15	$127.10
7 purchase totals =	$963.59		$1,061.3743	$1,061.38	$1,061.40	$1,061.30