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	$176.63	12.758%	$199.1645	$199.16	$199.15	$199.20
Purchase #2	$72.47	5.584%	$76.5167	$76.52	$76.50	$76.50
Purchase #3	$73.80	6.762%	$78.7904	$78.79	$78.80	$78.80
Purchase #4	$233.94	11.709%	$261.332	$261.33	$261.35	$261.30
Purchase #5	$245.39	8.710%	$266.7635	$266.76	$266.75	$266.80
Purchase #6	$141.41	4.703%	$148.0605	$148.06	$148.05	$148.10
Purchase #7	$29.42	5.439%	$31.0202	$31.02	$31.00	$31.00
7 purchase totals =	$973.06		$1,061.6478	$1,061.64	$1,061.60	$1,061.70