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	$214.95	11.201%	$239.0265	$239.03	$239.05	$239.00
Purchase #2	$155.83	12.656%	$175.5518	$175.55	$175.55	$175.60
Purchase #3	$199.71	6.403%	$212.4974	$212.50	$212.50	$212.50
Purchase #4	$214.95	6.492%	$228.9046	$228.90	$228.90	$228.90
Purchase #5	$95.59	8.763%	$103.9666	$103.97	$103.95	$104.00
Purchase #6	$10.27	6.772%	$10.9655	$10.97	$10.95	$11.00
Purchase #7	$84.47	7.469%	$90.7791	$90.78	$90.80	$90.80
7 purchase totals =	$975.77		$1,061.6915	$1,061.70	$1,061.70	$1,061.80