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	$243.58	7.874%	$262.7595	$262.76	$262.75	$262.80
Purchase #2	$122.32	3.737%	$126.8911	$126.89	$126.90	$126.90
Purchase #3	$196.60	6.767%	$209.9039	$209.90	$209.90	$209.90
Purchase #4	$56.59	5.665%	$59.7958	$59.80	$59.80	$59.80
Purchase #5	$211.51	13.797%	$240.692	$240.69	$240.70	$240.70
Purchase #6	$217.39	12.491%	$244.5442	$244.54	$244.55	$244.50
Purchase #7	$13.33	11.292%	$14.8352	$14.84	$14.85	$14.80
7 purchase totals =	$1,061.32		$1,159.4217	$1,159.42	$1,159.45	$1,159.40