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	$231.43	13.214%	$262.0112	$262.01	$262.00	$262.00
Purchase #2	$49.70	7.712%	$53.5329	$53.53	$53.55	$53.50
Purchase #3	$19.26	9.161%	$21.0244	$21.02	$21.00	$21.00
Purchase #4	$89.92	9.166%	$98.1621	$98.16	$98.15	$98.20
Purchase #5	$200.59	8.315%	$217.2691	$217.27	$217.25	$217.30
Purchase #6	$116.29	13.631%	$132.1415	$132.14	$132.15	$132.10
Purchase #7	$77.31	10.716%	$85.5945	$85.59	$85.60	$85.60
7 purchase totals =	$784.50		$869.7357	$869.72	$869.70	$869.70