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	$215.67	13.861%	$245.564	$245.56	$245.55	$245.60
Purchase #2	$29.65	12.347%	$33.3109	$33.31	$33.30	$33.30
Purchase #3	$110.98	11.332%	$123.5563	$123.56	$123.55	$123.60
Purchase #4	$188.99	3.733%	$196.045	$196.05	$196.05	$196.00
Purchase #5	$99.92	11.622%	$111.5327	$111.53	$111.55	$111.50
Purchase #6	$153.91	13.361%	$174.4739	$174.47	$174.45	$174.50
Purchase #7	$196.47	10.703%	$217.4982	$217.50	$217.50	$217.50
7 purchase totals =	$995.59		$1,101.9810	$1,101.98	$1,101.95	$1,102.00