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	$141.36	4.748%	$148.0718	$148.07	$148.05	$148.10
Purchase #2	$220.51	11.323%	$245.4783	$245.48	$245.50	$245.50
Purchase #3	$174.41	9.223%	$190.4958	$190.50	$190.50	$190.50
Purchase #4	$58.67	8.866%	$63.8717	$63.87	$63.85	$63.90
Purchase #5	$146.83	12.692%	$165.4657	$165.47	$165.45	$165.50
Purchase #6	$164.63	7.314%	$176.671	$176.67	$176.65	$176.70
Purchase #7	$85.42	8.253%	$92.4697	$92.47	$92.45	$92.50
7 purchase totals =	$991.83		$1,082.5240	$1,082.53	$1,082.45	$1,082.70