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	$56.96	9.433%	$62.333	$62.33	$62.35	$62.30
Purchase #2	$10.45	12.696%	$11.7767	$11.78	$11.80	$11.80
Purchase #3	$98.67	6.236%	$104.8231	$104.82	$104.80	$104.80
Purchase #4	$42.62	6.803%	$45.5194	$45.52	$45.50	$45.50
Purchase #5	$120.28	5.298%	$126.6524	$126.65	$126.65	$126.70
Purchase #6	$206.92	8.151%	$223.786	$223.79	$223.80	$223.80
Purchase #7	$11.60	7.353%	$12.4529	$12.45	$12.45	$12.50
7 purchase totals =	$547.50		$587.3435	$587.34	$587.35	$587.40