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	$81.52	5.171%	$85.7354	$85.74	$85.75	$85.70
Purchase #2	$212.77	5.183%	$223.7979	$223.80	$223.80	$223.80
Purchase #3	$205.82	6.659%	$219.5256	$219.53	$219.55	$219.50
Purchase #4	$11.37	6.575%	$12.1176	$12.12	$12.10	$12.10
Purchase #5	$53.91	8.720%	$58.611	$58.61	$58.60	$58.60
Purchase #6	$102.31	7.187%	$109.663	$109.66	$109.65	$109.70
Purchase #7	$50.45	12.174%	$56.5918	$56.59	$56.60	$56.60
7 purchase totals =	$718.15		$766.0423	$766.05	$766.05	$766.00