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	$77.50	12.284%	$87.0201	$87.02	$87.00	$87.00
Purchase #2	$134.92	8.299%	$146.117	$146.12	$146.10	$146.10
Purchase #3	$181.35	4.429%	$189.382	$189.38	$189.40	$189.40
Purchase #4	$187.90	6.742%	$200.5682	$200.57	$200.55	$200.60
Purchase #5	$187.33	5.454%	$197.547	$197.55	$197.55	$197.50
Purchase #6	$126.38	5.141%	$132.8772	$132.88	$132.90	$132.90
Purchase #7	$55.78	11.163%	$62.0067	$62.01	$62.00	$62.00
7 purchase totals =	$951.16		$1,015.5182	$1,015.53	$1,015.50	$1,015.50