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	$208.77	9.280%	$228.1439	$228.14	$228.15	$228.10
Purchase #2	$215.26	8.499%	$233.5549	$233.55	$233.55	$233.60
Purchase #3	$227.30	12.748%	$256.2762	$256.28	$256.30	$256.30
Purchase #4	$134.45	12.393%	$151.1124	$151.11	$151.10	$151.10
Purchase #5	$242.43	12.679%	$273.1677	$273.17	$273.15	$273.20
Purchase #6	$144.55	13.863%	$164.589	$164.59	$164.60	$164.60
Purchase #7	$233.82	12.484%	$263.0101	$263.01	$263.00	$263.00
7 purchase totals =	$1,406.58		$1,569.8542	$1,569.85	$1,569.85	$1,569.90