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	$107.33	3.553%	$111.1434	$111.14	$111.15	$111.10
Purchase #2	$10.47	10.622%	$11.5821	$11.58	$11.60	$11.60
Purchase #3	$232.28	13.468%	$263.5635	$263.56	$263.55	$263.60
Purchase #4	$242.35	3.377%	$250.5342	$250.53	$250.55	$250.50
Purchase #5	$240.52	4.372%	$251.0355	$251.04	$251.05	$251.00
Purchase #6	$24.88	11.704%	$27.792	$27.79	$27.80	$27.80
Purchase #7	$27.40	13.544%	$31.1111	$31.11	$31.10	$31.10
7 purchase totals =	$885.23		$946.7618	$946.75	$946.80	$946.70