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	$241.82	8.525%	$262.4352	$262.44	$262.45	$262.40
Purchase #2	$37.37	9.226%	$40.8178	$40.82	$40.80	$40.80
Purchase #3	$99.45	3.490%	$102.9208	$102.92	$102.90	$102.90
Purchase #4	$248.38	10.643%	$274.8151	$274.82	$274.80	$274.80
Purchase #5	$19.35	12.196%	$21.7099	$21.71	$21.70	$21.70
Purchase #6	$217.46	4.663%	$227.6002	$227.60	$227.60	$227.60
Purchase #7	$114.41	10.270%	$126.1599	$126.16	$126.15	$126.20
7 purchase totals =	$978.24		$1,056.4589	$1,056.47	$1,056.40	$1,056.40