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	$87.64	9.578%	$96.0342	$96.03	$96.05	$96.00
Purchase #2	$151.76	13.592%	$172.3872	$172.39	$172.40	$172.40
Purchase #3	$130.25	8.730%	$141.6208	$141.62	$141.60	$141.60
Purchase #4	$134.53	7.789%	$145.0085	$145.01	$145.00	$145.00
Purchase #5	$157.63	9.642%	$172.8287	$172.83	$172.85	$172.80
Purchase #6	$41.64	4.831%	$43.6516	$43.65	$43.65	$43.70
Purchase #7	$112.88	10.758%	$125.0236	$125.02	$125.00	$125.00
7 purchase totals =	$816.33		$896.5546	$896.55	$896.55	$896.50