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	$84.58	12.792%	$95.3995	$95.40	$95.40	$95.40
Purchase #2	$192.82	12.826%	$217.5511	$217.55	$217.55	$217.60
Purchase #3	$145.88	3.394%	$150.8312	$150.83	$150.85	$150.80
Purchase #4	$101.61	3.632%	$105.3005	$105.30	$105.30	$105.30
Purchase #5	$157.79	12.139%	$176.9441	$176.94	$176.95	$176.90
Purchase #6	$54.52	5.722%	$57.6396	$57.64	$57.65	$57.60
Purchase #7	$60.71	7.624%	$65.3385	$65.34	$65.35	$65.30
7 purchase totals =	$797.91		$869.0045	$869.00	$869.05	$868.90