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	$86.61	11.158%	$96.2739	$96.27	$96.25	$96.30
Purchase #2	$10.82	5.186%	$11.3811	$11.38	$11.40	$11.40
Purchase #3	$65.85	4.341%	$68.7085	$68.71	$68.70	$68.70
Purchase #4	$31.39	7.705%	$33.8086	$33.81	$33.80	$33.80
Purchase #5	$48.91	5.134%	$51.421	$51.42	$51.40	$51.40
Purchase #6	$101.91	9.506%	$111.5976	$111.60	$111.60	$111.60
Purchase #7	$12.86	7.770%	$13.8592	$13.86	$13.85	$13.90
7 purchase totals =	$358.35		$387.0499	$387.05	$387.00	$387.10