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	$127.26	12.131%	$142.6979	$142.70	$142.70	$142.70
Purchase #2	$126.48	3.719%	$131.1838	$131.18	$131.20	$131.20
Purchase #3	$13.94	11.667%	$15.5664	$15.57	$15.55	$15.60
Purchase #4	$153.32	11.709%	$171.2722	$171.27	$171.25	$171.30
Purchase #5	$208.39	11.874%	$233.1342	$233.13	$233.15	$233.10
Purchase #6	$81.90	6.707%	$87.393	$87.39	$87.40	$87.40
Purchase #7	$239.38	6.857%	$255.7943	$255.79	$255.80	$255.80
7 purchase totals =	$950.67		$1,037.0418	$1,037.03	$1,037.05	$1,037.10