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	$43.81	4.239%	$45.6671	$45.67	$45.65	$45.70
Purchase #2	$214.78	6.229%	$228.1586	$228.16	$228.15	$228.20
Purchase #3	$208.56	10.788%	$231.0595	$231.06	$231.05	$231.10
Purchase #4	$211.59	11.871%	$236.7078	$236.71	$236.70	$236.70
Purchase #5	$44.30	4.215%	$46.1672	$46.17	$46.15	$46.20
Purchase #6	$184.82	8.515%	$200.5574	$200.56	$200.55	$200.60
Purchase #7	$13.42	5.172%	$14.1141	$14.11	$14.10	$14.10
7 purchase totals =	$921.28		$1,002.4317	$1,002.44	$1,002.35	$1,002.60