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	$210.44	11.536%	$234.7164	$234.72	$234.70	$234.70
Purchase #2	$208.30	11.304%	$231.8462	$231.85	$231.85	$231.80
Purchase #3	$55.25	3.116%	$56.9716	$56.97	$56.95	$57.00
Purchase #4	$217.94	4.553%	$227.8628	$227.86	$227.85	$227.90
Purchase #5	$71.42	9.782%	$78.4063	$78.41	$78.40	$78.40
Purchase #6	$92.29	13.268%	$104.535	$104.54	$104.55	$104.50
Purchase #7	$182.51	4.224%	$190.2192	$190.22	$190.20	$190.20
7 purchase totals =	$1,038.15		$1,124.5575	$1,124.57	$1,124.50	$1,124.50