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	$44.52	4.196%	$46.3881	$46.39	$46.40	$46.40
Purchase #2	$45.45	11.371%	$50.6181	$50.62	$50.60	$50.60
Purchase #3	$7.38	5.334%	$7.7736	$7.77	$7.75	$7.80
Purchase #4	$190.58	13.576%	$216.4531	$216.45	$216.45	$216.50
Purchase #5	$26.25	3.225%	$27.0966	$27.10	$27.10	$27.10
Purchase #6	$35.65	6.627%	$38.0125	$38.01	$38.00	$38.00
Purchase #7	$95.82	6.544%	$102.0905	$102.09	$102.10	$102.10
7 purchase totals =	$445.65		$488.4325	$488.43	$488.40	$488.50