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	$214.76	12.560%	$241.7339	$241.73	$241.75	$241.70
Purchase #2	$118.98	3.429%	$123.0598	$123.06	$123.05	$123.10
Purchase #3	$63.96	11.120%	$71.0724	$71.07	$71.05	$71.10
Purchase #4	$19.39	9.186%	$21.1712	$21.17	$21.15	$21.20
Purchase #5	$73.32	9.168%	$80.042	$80.04	$80.05	$80.00
Purchase #6	$158.90	6.844%	$169.7751	$169.78	$169.80	$169.80
Purchase #7	$46.51	13.119%	$52.6116	$52.61	$52.60	$52.60
7 purchase totals =	$695.82		$759.4660	$759.46	$759.45	$759.50