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	$182.97	7.312%	$196.3488	$196.35	$196.35	$196.30
Purchase #2	$118.81	10.422%	$131.1924	$131.19	$131.20	$131.20
Purchase #3	$95.70	8.492%	$103.8268	$103.83	$103.85	$103.80
Purchase #4	$83.77	3.324%	$86.5545	$86.55	$86.55	$86.60
Purchase #5	$56.78	13.758%	$64.5918	$64.59	$64.60	$64.60
Purchase #6	$66.34	7.471%	$71.2963	$71.30	$71.30	$71.30
Purchase #7	$43.87	11.204%	$48.7852	$48.79	$48.80	$48.80
7 purchase totals =	$648.24		$702.5958	$702.60	$702.65	$702.60