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	$203.77	6.528%	$217.0721	$217.07	$217.05	$217.10
Purchase #2	$137.96	10.575%	$152.5493	$152.55	$152.55	$152.50
Purchase #3	$212.35	8.546%	$230.4974	$230.50	$230.50	$230.50
Purchase #4	$92.76	3.565%	$96.0669	$96.07	$96.05	$96.10
Purchase #5	$86.96	3.141%	$89.6914	$89.69	$89.70	$89.70
Purchase #6	$47.99	4.376%	$50.09	$50.09	$50.10	$50.10
Purchase #7	$52.36	13.394%	$59.3731	$59.37	$59.35	$59.40
7 purchase totals =	$834.15		$895.3402	$895.34	$895.30	$895.40