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	$111.71	12.500%	$125.6738	$125.67	$125.65	$125.70
Purchase #2	$97.38	3.155%	$100.4523	$100.45	$100.45	$100.50
Purchase #3	$68.33	12.765%	$77.0523	$77.05	$77.05	$77.10
Purchase #4	$219.60	4.387%	$229.2339	$229.23	$229.25	$229.20
Purchase #5	$215.62	7.202%	$231.149	$231.15	$231.15	$231.10
Purchase #6	$125.83	4.181%	$131.091	$131.09	$131.10	$131.10
Purchase #7	$29.42	11.667%	$32.8524	$32.85	$32.85	$32.90
7 purchase totals =	$867.89		$927.5047	$927.49	$927.50	$927.60