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	$100.39	3.426%	$103.8294	$103.83	$103.85	$103.80
Purchase #2	$89.99	7.626%	$96.8526	$96.85	$96.85	$96.90
Purchase #3	$11.41	10.717%	$12.6328	$12.63	$12.65	$12.60
Purchase #4	$47.98	3.858%	$49.8311	$49.83	$49.85	$49.80
Purchase #5	$227.79	12.645%	$256.594	$256.59	$256.60	$256.60
Purchase #6	$62.98	7.697%	$67.8276	$67.83	$67.85	$67.80
Purchase #7	$116.88	7.811%	$126.0095	$126.01	$126.00	$126.00
7 purchase totals =	$657.42		$713.5770	$713.57	$713.65	$713.50