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	$196.89	9.522%	$215.6379	$215.64	$215.65	$215.60
Purchase #2	$154.92	10.423%	$171.0673	$171.07	$171.05	$171.10
Purchase #3	$6.99	7.365%	$7.5048	$7.50	$7.50	$7.50
Purchase #4	$45.85	13.590%	$52.081	$52.08	$52.10	$52.10
Purchase #5	$64.44	8.477%	$69.9026	$69.90	$69.90	$69.90
Purchase #6	$170.37	13.162%	$192.7941	$192.79	$192.80	$192.80
Purchase #7	$56.89	3.761%	$59.0296	$59.03	$59.05	$59.00
7 purchase totals =	$696.35		$768.0173	$768.01	$768.05	$768.00