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	$173.67	13.123%	$196.4607	$196.46	$196.45	$196.50
Purchase #2	$86.53	6.431%	$92.0947	$92.09	$92.10	$92.10
Purchase #3	$232.85	7.201%	$249.6175	$249.62	$249.60	$249.60
Purchase #4	$132.82	9.137%	$144.9558	$144.96	$144.95	$145.00
Purchase #5	$194.43	12.296%	$218.3371	$218.34	$218.35	$218.30
Purchase #6	$114.48	7.415%	$122.9687	$122.97	$122.95	$123.00
Purchase #7	$38.65	12.553%	$43.5017	$43.50	$43.50	$43.50
7 purchase totals =	$973.43		$1,067.9362	$1,067.94	$1,067.90	$1,068.00