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	$12.41	13.213%	$14.0497	$14.05	$14.05	$14.00
Purchase #2	$227.82	6.861%	$243.4507	$243.45	$243.45	$243.50
Purchase #3	$76.86	6.462%	$81.8267	$81.83	$81.85	$81.80
Purchase #4	$91.67	9.817%	$100.6692	$100.67	$100.65	$100.70
Purchase #5	$111.99	12.189%	$125.6405	$125.64	$125.65	$125.60
Purchase #6	$103.40	8.142%	$111.8188	$111.82	$111.80	$111.80
Purchase #7	$243.58	3.245%	$251.4842	$251.48	$251.50	$251.50
7 purchase totals =	$867.73		$928.9398	$928.94	$928.95	$928.90