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	$226.39	5.218%	$238.203	$238.20	$238.20	$238.20
Purchase #2	$62.51	6.273%	$66.4313	$66.43	$66.45	$66.40
Purchase #3	$221.89	13.789%	$252.4864	$252.49	$252.50	$252.50
Purchase #4	$48.27	3.446%	$49.9334	$49.93	$49.95	$49.90
Purchase #5	$52.75	4.587%	$55.1696	$55.17	$55.15	$55.20
Purchase #6	$181.64	10.615%	$200.9211	$200.92	$200.90	$200.90
Purchase #7	$248.44	6.508%	$264.6085	$264.61	$264.60	$264.60
7 purchase totals =	$1,041.89		$1,127.7533	$1,127.75	$1,127.75	$1,127.70