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	$136.43	6.243%	$144.9473	$144.95	$144.95	$144.90
Purchase #2	$87.29	8.106%	$94.3657	$94.37	$94.35	$94.40
Purchase #3	$129.93	4.196%	$135.3819	$135.38	$135.40	$135.40
Purchase #4	$170.83	5.206%	$179.7234	$179.72	$179.70	$179.70
Purchase #5	$94.64	11.304%	$105.3381	$105.34	$105.35	$105.30
Purchase #6	$238.60	6.382%	$253.8275	$253.83	$253.85	$253.80
Purchase #7	$102.35	8.470%	$111.019	$111.02	$111.00	$111.00
7 purchase totals =	$960.07		$1,024.6029	$1,024.61	$1,024.60	$1,024.50