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	$32.51	5.687%	$34.3588	$34.36	$34.35	$34.40
Purchase #2	$73.82	11.160%	$82.0583	$82.06	$82.05	$82.10
Purchase #3	$62.93	5.585%	$66.4446	$66.44	$66.45	$66.40
Purchase #4	$62.95	5.567%	$66.4544	$66.45	$66.45	$66.50
Purchase #5	$94.73	6.158%	$100.5635	$100.56	$100.55	$100.60
Purchase #6	$84.35	13.447%	$95.6925	$95.69	$95.70	$95.70
Purchase #7	$49.43	3.236%	$51.0296	$51.03	$51.05	$51.00
7 purchase totals =	$460.72		$496.6017	$496.59	$496.60	$496.70