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	$53.95	10.480%	$59.604	$59.60	$59.60	$59.60
Purchase #2	$152.46	4.391%	$159.1545	$159.15	$159.15	$159.20
Purchase #3	$238.86	10.709%	$264.4395	$264.44	$264.45	$264.40
Purchase #4	$53.85	11.526%	$60.0568	$60.06	$60.05	$60.10
Purchase #5	$217.95	12.650%	$245.5207	$245.52	$245.50	$245.50
Purchase #6	$74.79	9.468%	$81.8711	$81.87	$81.85	$81.90
Purchase #7	$77.77	5.126%	$81.7565	$81.76	$81.75	$81.80
7 purchase totals =	$869.63		$952.4031	$952.40	$952.35	$952.50