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	$199.49	13.810%	$227.0396	$227.04	$227.05	$227.00
Purchase #2	$117.82	11.710%	$131.6167	$131.62	$131.60	$131.60
Purchase #3	$122.98	12.105%	$137.8667	$137.87	$137.85	$137.90
Purchase #4	$183.64	5.714%	$194.1332	$194.13	$194.15	$194.10
Purchase #5	$128.35	9.617%	$140.6934	$140.69	$140.70	$140.70
Purchase #6	$89.88	4.566%	$93.9839	$93.98	$94.00	$94.00
Purchase #7	$86.59	8.828%	$94.2342	$94.23	$94.25	$94.20
7 purchase totals =	$928.75		$1,019.5677	$1,019.56	$1,019.60	$1,019.50