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	$12.69	11.580%	$14.1595	$14.16	$14.15	$14.20
Purchase #2	$86.32	5.293%	$90.8889	$90.89	$90.90	$90.90
Purchase #3	$177.33	3.477%	$183.4958	$183.50	$183.50	$183.50
Purchase #4	$12.29	8.836%	$13.3759	$13.38	$13.40	$13.40
Purchase #5	$135.91	11.834%	$151.9936	$151.99	$152.00	$152.00
Purchase #6	$210.59	4.396%	$219.8475	$219.85	$219.85	$219.80
Purchase #7	$34.31	12.769%	$38.691	$38.69	$38.70	$38.70
7 purchase totals =	$669.44		$712.4522	$712.46	$712.50	$712.50