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	$193.46	11.330%	$215.379	$215.38	$215.40	$215.40
Purchase #2	$116.97	4.263%	$121.9564	$121.96	$121.95	$122.00
Purchase #3	$101.66	3.293%	$105.0077	$105.01	$105.00	$105.00
Purchase #4	$248.69	4.481%	$259.8338	$259.83	$259.85	$259.80
Purchase #5	$139.48	6.490%	$148.5323	$148.53	$148.55	$148.50
Purchase #6	$146.54	8.799%	$159.4341	$159.43	$159.45	$159.40
Purchase #7	$177.73	10.383%	$196.1837	$196.18	$196.20	$196.20
7 purchase totals =	$1,124.53		$1,206.3270	$1,206.32	$1,206.40	$1,206.30