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	$216.72	8.199%	$234.4889	$234.49	$234.50	$234.50
Purchase #2	$208.90	4.727%	$218.7747	$218.77	$218.75	$218.80
Purchase #3	$85.26	5.426%	$89.8862	$89.89	$89.90	$89.90
Purchase #4	$200.49	6.631%	$213.7845	$213.78	$213.80	$213.80
Purchase #5	$49.30	4.683%	$51.6087	$51.61	$51.60	$51.60
Purchase #6	$37.61	8.671%	$40.8712	$40.87	$40.85	$40.90
Purchase #7	$159.56	9.451%	$174.64	$174.64	$174.65	$174.60
7 purchase totals =	$957.84		$1,024.0542	$1,024.05	$1,024.05	$1,024.10