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	$177.59	10.694%	$196.5815	$196.58	$196.60	$196.60
Purchase #2	$222.32	6.562%	$236.9086	$236.91	$236.90	$236.90
Purchase #3	$50.50	8.519%	$54.8021	$54.80	$54.80	$54.80
Purchase #4	$134.25	11.789%	$150.0767	$150.08	$150.10	$150.10
Purchase #5	$171.67	6.284%	$182.4577	$182.46	$182.45	$182.50
Purchase #6	$145.44	12.280%	$163.3	$163.30	$163.30	$163.30
Purchase #7	$100.97	10.870%	$111.9454	$111.95	$111.95	$111.90
7 purchase totals =	$1,002.74		$1,096.0720	$1,096.08	$1,096.10	$1,096.10