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	$119.60	6.695%	$127.6072	$127.61	$127.60	$127.60
Purchase #2	$60.76	8.548%	$65.9538	$65.95	$65.95	$66.00
Purchase #3	$217.76	5.753%	$230.2877	$230.29	$230.30	$230.30
Purchase #4	$202.45	6.653%	$215.919	$215.92	$215.90	$215.90
Purchase #5	$216.75	5.390%	$228.4328	$228.43	$228.45	$228.40
Purchase #6	$13.88	13.836%	$15.8004	$15.80	$15.80	$15.80
Purchase #7	$189.69	11.307%	$211.1382	$211.14	$211.15	$211.10
7 purchase totals =	$1,020.89		$1,095.1391	$1,095.14	$1,095.15	$1,095.10