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	$176.48	11.135%	$196.131	$196.13	$196.15	$196.10
Purchase #2	$94.88	10.223%	$104.5796	$104.58	$104.60	$104.60
Purchase #3	$63.38	8.343%	$68.6678	$68.67	$68.65	$68.70
Purchase #4	$41.30	8.567%	$44.8382	$44.84	$44.85	$44.80
Purchase #5	$157.38	6.704%	$167.9308	$167.93	$167.95	$167.90
Purchase #6	$10.83	6.373%	$11.5202	$11.52	$11.50	$11.50
Purchase #7	$77.98	3.642%	$80.82	$80.82	$80.80	$80.80
7 purchase totals =	$622.23		$674.4876	$674.49	$674.50	$674.40