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	$39.65	4.539%	$41.4497	$41.45	$41.45	$41.40
Purchase #2	$69.27	3.376%	$71.6086	$71.61	$71.60	$71.60
Purchase #3	$102.86	4.189%	$107.1688	$107.17	$107.15	$107.20
Purchase #4	$244.80	3.561%	$253.5173	$253.52	$253.50	$253.50
Purchase #5	$78.55	5.466%	$82.8435	$82.84	$82.85	$82.80
Purchase #6	$130.29	8.329%	$141.1419	$141.14	$141.15	$141.10
Purchase #7	$204.27	4.620%	$213.7073	$213.71	$213.70	$213.70
7 purchase totals =	$869.69		$911.4371	$911.44	$911.40	$911.30