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	$239.33	7.361%	$256.9471	$256.95	$256.95	$256.90
Purchase #2	$45.79	7.523%	$49.2348	$49.23	$49.25	$49.20
Purchase #3	$226.46	11.249%	$251.9345	$251.93	$251.95	$251.90
Purchase #4	$54.89	11.285%	$61.0843	$61.08	$61.10	$61.10
Purchase #5	$186.37	5.293%	$196.2346	$196.23	$196.25	$196.20
Purchase #6	$140.42	3.159%	$144.8559	$144.86	$144.85	$144.90
Purchase #7	$7.70	4.618%	$8.0556	$8.06	$8.05	$8.10
7 purchase totals =	$900.96		$968.3468	$968.34	$968.40	$968.30