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	$148.25	11.592%	$165.4351	$165.44	$165.45	$165.40
Purchase #2	$48.31	11.793%	$54.0072	$54.01	$54.00	$54.00
Purchase #3	$154.43	13.378%	$175.0896	$175.09	$175.10	$175.10
Purchase #4	$52.46	6.478%	$55.8584	$55.86	$55.85	$55.90
Purchase #5	$214.46	4.590%	$224.3037	$224.30	$224.30	$224.30
Purchase #6	$212.48	4.768%	$222.611	$222.61	$222.60	$222.60
Purchase #7	$155.63	9.126%	$169.8328	$169.83	$169.85	$169.80
7 purchase totals =	$986.02		$1,067.1378	$1,067.14	$1,067.15	$1,067.10