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	$243.59	8.213%	$263.596	$263.60	$263.60	$263.60
Purchase #2	$40.55	12.754%	$45.7217	$45.72	$45.70	$45.70
Purchase #3	$44.81	10.292%	$49.4218	$49.42	$49.40	$49.40
Purchase #4	$158.45	10.651%	$175.3265	$175.33	$175.35	$175.30
Purchase #5	$133.93	13.432%	$151.9195	$151.92	$151.90	$151.90
Purchase #6	$236.81	8.241%	$256.3255	$256.33	$256.35	$256.30
Purchase #7	$237.30	10.550%	$262.3352	$262.34	$262.35	$262.30
7 purchase totals =	$1,095.44		$1,204.6462	$1,204.66	$1,204.65	$1,204.50