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	$177.32	11.129%	$197.0539	$197.05	$197.05	$197.10
Purchase #2	$142.96	7.520%	$153.7106	$153.71	$153.70	$153.70
Purchase #3	$144.82	10.379%	$159.8509	$159.85	$159.85	$159.90
Purchase #4	$11.52	13.179%	$13.0382	$13.04	$13.05	$13.00
Purchase #5	$46.75	12.705%	$52.6896	$52.69	$52.70	$52.70
Purchase #6	$189.25	3.573%	$196.0119	$196.01	$196.00	$196.00
Purchase #7	$239.48	10.477%	$264.5703	$264.57	$264.55	$264.60
7 purchase totals =	$952.10		$1,036.9254	$1,036.92	$1,036.90	$1,037.00