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	$206.81	3.767%	$214.6005	$214.60	$214.60	$214.60
Purchase #2	$116.31	3.656%	$120.5623	$120.56	$120.55	$120.60
Purchase #3	$59.75	3.459%	$61.8168	$61.82	$61.80	$61.80
Purchase #4	$112.49	5.191%	$118.3294	$118.33	$118.35	$118.30
Purchase #5	$172.47	7.431%	$185.2862	$185.29	$185.30	$185.30
Purchase #6	$75.78	6.224%	$80.4965	$80.50	$80.50	$80.50
Purchase #7	$191.28	12.121%	$214.465	$214.47	$214.45	$214.50
7 purchase totals =	$934.89		$995.5567	$995.57	$995.55	$995.60