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	$55.38	11.206%	$61.5859	$61.59	$61.60	$61.60
Purchase #2	$153.50	10.599%	$169.7695	$169.77	$169.75	$169.80
Purchase #3	$246.86	10.564%	$272.9383	$272.94	$272.95	$272.90
Purchase #4	$16.68	11.344%	$18.5722	$18.57	$18.55	$18.60
Purchase #5	$129.44	5.702%	$136.8207	$136.82	$136.80	$136.80
Purchase #6	$81.87	3.839%	$85.013	$85.01	$85.00	$85.00
Purchase #7	$237.56	10.570%	$262.6701	$262.67	$262.65	$262.70
7 purchase totals =	$921.29		$1,007.3697	$1,007.37	$1,007.30	$1,007.40