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	$172.64	11.275%	$192.1052	$192.11	$192.10	$192.10
Purchase #2	$157.72	6.495%	$167.9639	$167.96	$167.95	$168.00
Purchase #3	$149.89	5.725%	$158.4712	$158.47	$158.45	$158.50
Purchase #4	$191.63	7.249%	$205.5213	$205.52	$205.50	$205.50
Purchase #5	$65.27	8.666%	$70.9263	$70.93	$70.95	$70.90
Purchase #6	$167.98	6.158%	$178.3242	$178.32	$178.30	$178.30
Purchase #7	$192.28	10.178%	$211.8503	$211.85	$211.85	$211.90
7 purchase totals =	$1,097.41		$1,185.1624	$1,185.16	$1,185.10	$1,185.20