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	$231.70	5.512%	$244.4713	$244.47	$244.45	$244.50
Purchase #2	$83.50	12.722%	$94.1229	$94.12	$94.10	$94.10
Purchase #3	$20.85	4.516%	$21.7916	$21.79	$21.80	$21.80
Purchase #4	$91.43	9.835%	$100.4221	$100.42	$100.40	$100.40
Purchase #5	$190.28	13.698%	$216.3446	$216.34	$216.35	$216.30
Purchase #6	$102.77	13.318%	$116.4569	$116.46	$116.45	$116.50
Purchase #7	$84.35	9.605%	$92.4518	$92.45	$92.45	$92.50
7 purchase totals =	$804.88		$886.0612	$886.05	$886.00	$886.10