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	$96.86	8.329%	$104.9275	$104.93	$104.95	$104.90
Purchase #2	$63.84	13.328%	$72.3486	$72.35	$72.35	$72.30
Purchase #3	$77.36	12.291%	$86.8683	$86.87	$86.85	$86.90
Purchase #4	$40.54	13.397%	$45.9711	$45.97	$45.95	$46.00
Purchase #5	$213.36	6.761%	$227.7853	$227.79	$227.80	$227.80
Purchase #6	$106.86	8.131%	$115.5488	$115.55	$115.55	$115.50
Purchase #7	$56.89	13.463%	$64.5491	$64.55	$64.55	$64.50
7 purchase totals =	$655.71		$717.9987	$718.01	$718.00	$717.90