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	$180.49	6.776%	$192.72	$192.72	$192.70	$192.70
Purchase #2	$67.51	5.861%	$71.4668	$71.47	$71.45	$71.50
Purchase #3	$160.29	8.371%	$173.7079	$173.71	$173.70	$173.70
Purchase #4	$196.83	9.151%	$214.8419	$214.84	$214.85	$214.80
Purchase #5	$105.62	5.637%	$111.5738	$111.57	$111.55	$111.60
Purchase #6	$190.63	4.626%	$199.4485	$199.45	$199.45	$199.40
Purchase #7	$163.46	5.269%	$172.0727	$172.07	$172.05	$172.10
7 purchase totals =	$1,064.83		$1,135.8316	$1,135.83	$1,135.75	$1,135.80