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	$103.46	10.183%	$113.9953	$114.00	$114.00	$114.00
Purchase #2	$196.49	10.735%	$217.5832	$217.58	$217.60	$217.60
Purchase #3	$116.38	12.526%	$130.9578	$130.96	$130.95	$131.00
Purchase #4	$42.99	6.581%	$45.8192	$45.82	$45.80	$45.80
Purchase #5	$248.70	10.783%	$275.5173	$275.52	$275.50	$275.50
Purchase #6	$159.61	11.475%	$177.9252	$177.93	$177.95	$177.90
Purchase #7	$86.93	12.821%	$98.0753	$98.08	$98.10	$98.10
7 purchase totals =	$954.56		$1,059.8733	$1,059.89	$1,059.90	$1,059.90