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	$40.59	10.111%	$44.6941	$44.69	$44.70	$44.70
Purchase #2	$208.68	3.253%	$215.4684	$215.47	$215.45	$215.50
Purchase #3	$89.37	11.512%	$99.6583	$99.66	$99.65	$99.70
Purchase #4	$110.65	5.360%	$116.5808	$116.58	$116.60	$116.60
Purchase #5	$23.45	9.194%	$25.606	$25.61	$25.60	$25.60
Purchase #6	$29.35	8.539%	$31.8562	$31.86	$31.85	$31.90
Purchase #7	$154.28	4.738%	$161.5898	$161.59	$161.60	$161.60
7 purchase totals =	$656.37		$695.4536	$695.46	$695.45	$695.60