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	$196.43	10.165%	$216.3971	$216.40	$216.40	$216.40
Purchase #2	$41.82	3.677%	$43.3577	$43.36	$43.35	$43.40
Purchase #3	$151.81	12.379%	$170.6026	$170.60	$170.60	$170.60
Purchase #4	$18.48	11.403%	$20.5873	$20.59	$20.60	$20.60
Purchase #5	$242.96	4.762%	$254.5298	$254.53	$254.55	$254.50
Purchase #6	$164.89	5.528%	$174.0051	$174.01	$174.00	$174.00
Purchase #7	$136.97	5.505%	$144.5102	$144.51	$144.50	$144.50
7 purchase totals =	$953.36		$1,023.9898	$1,024.00	$1,024.00	$1,024.00