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	$48.29	8.490%	$52.3898	$52.39	$52.40	$52.40
Purchase #2	$35.81	7.711%	$38.5713	$38.57	$38.55	$38.60
Purchase #3	$53.51	7.560%	$57.5554	$57.56	$57.55	$57.60
Purchase #4	$187.53	6.577%	$199.8638	$199.86	$199.85	$199.90
Purchase #5	$81.48	10.725%	$90.2187	$90.22	$90.20	$90.20
Purchase #6	$245.80	12.760%	$277.1641	$277.16	$277.15	$277.20
Purchase #7	$10.27	4.832%	$10.7662	$10.77	$10.75	$10.80
7 purchase totals =	$662.69		$726.5293	$726.53	$726.45	$726.70