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	$116.56	7.307%	$125.077	$125.08	$125.10	$125.10
Purchase #2	$11.92	4.347%	$12.4382	$12.44	$12.45	$12.40
Purchase #3	$150.75	10.464%	$166.5245	$166.52	$166.50	$166.50
Purchase #4	$98.82	12.793%	$111.462	$111.46	$111.45	$111.50
Purchase #5	$175.52	10.166%	$193.3634	$193.36	$193.35	$193.40
Purchase #6	$138.25	4.186%	$144.0371	$144.04	$144.05	$144.00
Purchase #7	$218.30	3.158%	$225.1939	$225.19	$225.20	$225.20
7 purchase totals =	$910.12		$978.0961	$978.09	$978.10	$978.10