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	$118.51	11.195%	$131.7772	$131.78	$131.80	$131.80
Purchase #2	$213.69	11.352%	$237.9481	$237.95	$237.95	$237.90
Purchase #3	$201.75	11.746%	$225.4476	$225.45	$225.45	$225.40
Purchase #4	$64.40	3.164%	$66.4376	$66.44	$66.45	$66.40
Purchase #5	$112.51	3.534%	$116.4861	$116.49	$116.50	$116.50
Purchase #6	$40.64	11.226%	$45.2022	$45.20	$45.20	$45.20
Purchase #7	$78.53	6.664%	$83.7632	$83.76	$83.75	$83.80
7 purchase totals =	$830.03		$907.0620	$907.07	$907.10	$907.00