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	$127.77	13.839%	$145.4521	$145.45	$145.45	$145.50
Purchase #2	$202.35	13.686%	$230.0436	$230.04	$230.05	$230.00
Purchase #3	$59.66	13.680%	$67.8215	$67.82	$67.80	$67.80
Purchase #4	$20.30	3.856%	$21.0828	$21.08	$21.10	$21.10
Purchase #5	$160.76	10.344%	$177.389	$177.39	$177.40	$177.40
Purchase #6	$150.76	12.484%	$169.5809	$169.58	$169.60	$169.60
Purchase #7	$191.53	11.801%	$214.1325	$214.13	$214.15	$214.10
7 purchase totals =	$913.13		$1,025.5024	$1,025.49	$1,025.55	$1,025.50