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	$85.45	11.265%	$95.0759	$95.08	$95.10	$95.10
Purchase #2	$119.52	6.681%	$127.5051	$127.51	$127.50	$127.50
Purchase #3	$82.48	8.302%	$89.3275	$89.33	$89.35	$89.30
Purchase #4	$82.82	4.599%	$86.6289	$86.63	$86.65	$86.60
Purchase #5	$100.26	3.205%	$103.4733	$103.47	$103.45	$103.50
Purchase #6	$242.51	5.514%	$255.882	$255.88	$255.90	$255.90
Purchase #7	$93.84	12.782%	$105.8346	$105.83	$105.85	$105.80
7 purchase totals =	$806.88		$863.7273	$863.73	$863.80	$863.70