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	$185.95	8.528%	$201.8078	$201.81	$201.80	$201.80
Purchase #2	$76.56	12.358%	$86.0213	$86.02	$86.00	$86.00
Purchase #3	$166.47	8.785%	$181.0944	$181.09	$181.10	$181.10
Purchase #4	$172.77	8.766%	$187.915	$187.92	$187.90	$187.90
Purchase #5	$130.60	10.472%	$144.2764	$144.28	$144.30	$144.30
Purchase #6	$187.86	4.615%	$196.5297	$196.53	$196.55	$196.50
Purchase #7	$133.33	11.583%	$148.7736	$148.77	$148.75	$148.80
7 purchase totals =	$1,053.54		$1,146.4182	$1,146.42	$1,146.40	$1,146.40