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	$163.69	5.517%	$172.7208	$172.72	$172.70	$172.70
Purchase #2	$25.27	11.362%	$28.1412	$28.14	$28.15	$28.10
Purchase #3	$34.41	11.669%	$38.4253	$38.43	$38.45	$38.40
Purchase #4	$66.77	8.679%	$72.565	$72.57	$72.55	$72.60
Purchase #5	$202.30	13.735%	$230.0859	$230.09	$230.10	$230.10
Purchase #6	$179.56	4.364%	$187.396	$187.40	$187.40	$187.40
Purchase #7	$132.61	7.519%	$142.5809	$142.58	$142.60	$142.60
7 purchase totals =	$804.61		$871.9151	$871.93	$871.95	$871.90