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	$214.40	5.373%	$225.9197	$225.92	$225.90	$225.90
Purchase #2	$26.50	10.637%	$29.3188	$29.32	$29.30	$29.30
Purchase #3	$111.68	13.456%	$126.7077	$126.71	$126.70	$126.70
Purchase #4	$200.89	4.744%	$210.4202	$210.42	$210.40	$210.40
Purchase #5	$100.51	4.642%	$105.1757	$105.18	$105.20	$105.20
Purchase #6	$176.77	8.848%	$192.4106	$192.41	$192.40	$192.40
Purchase #7	$157.54	9.171%	$171.988	$171.99	$172.00	$172.00
7 purchase totals =	$988.29		$1,061.9407	$1,061.95	$1,061.90	$1,061.90