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	$126.66	12.515%	$142.5115	$142.51	$142.50	$142.50
Purchase #2	$18.50	4.451%	$19.3234	$19.32	$19.30	$19.30
Purchase #3	$11.53	9.239%	$12.5953	$12.60	$12.60	$12.60
Purchase #4	$158.86	5.342%	$167.3463	$167.35	$167.35	$167.30
Purchase #5	$210.99	5.182%	$221.9235	$221.92	$221.90	$221.90
Purchase #6	$228.82	11.796%	$255.8116	$255.81	$255.80	$255.80
Purchase #7	$114.44	10.575%	$126.542	$126.54	$126.55	$126.50
7 purchase totals =	$869.80		$946.0536	$946.05	$946.00	$945.90