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	$84.52	12.477%	$95.0656	$95.07	$95.05	$95.10
Purchase #2	$30.94	4.301%	$32.2707	$32.27	$32.25	$32.30
Purchase #3	$101.86	10.320%	$112.372	$112.37	$112.35	$112.40
Purchase #4	$27.64	4.356%	$28.844	$28.84	$28.85	$28.80
Purchase #5	$60.53	11.436%	$67.4522	$67.45	$67.45	$67.50
Purchase #6	$46.77	4.466%	$48.8587	$48.86	$48.85	$48.90
Purchase #7	$220.83	4.181%	$230.0629	$230.06	$230.05	$230.10
7 purchase totals =	$573.09		$614.9261	$614.92	$614.85	$615.10