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	$244.50	7.465%	$262.7519	$262.75	$262.75	$262.80
Purchase #2	$97.65	6.392%	$103.8918	$103.89	$103.90	$103.90
Purchase #3	$148.68	9.445%	$162.7228	$162.72	$162.70	$162.70
Purchase #4	$64.34	6.188%	$68.3214	$68.32	$68.30	$68.30
Purchase #5	$144.66	12.536%	$162.7946	$162.79	$162.80	$162.80
Purchase #6	$145.27	4.678%	$152.0657	$152.07	$152.05	$152.10
Purchase #7	$11.60	11.562%	$12.9412	$12.94	$12.95	$12.90
7 purchase totals =	$856.70		$925.4894	$925.48	$925.45	$925.50