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	$59.31	10.617%	$65.6069	$65.61	$65.60	$65.60
Purchase #2	$183.33	9.423%	$200.6052	$200.61	$200.60	$200.60
Purchase #3	$10.35	9.630%	$11.3467	$11.35	$11.35	$11.30
Purchase #4	$178.85	8.516%	$194.0809	$194.08	$194.10	$194.10
Purchase #5	$198.77	4.648%	$208.0088	$208.01	$208.00	$208.00
Purchase #6	$53.33	4.200%	$55.5699	$55.57	$55.55	$55.60
Purchase #7	$242.94	7.766%	$261.8067	$261.81	$261.80	$261.80
7 purchase totals =	$926.88		$997.0251	$997.04	$997.00	$997.00