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	$23.53	9.865%	$25.8512	$25.85	$25.85	$25.90
Purchase #2	$34.58	8.801%	$37.6234	$37.62	$37.60	$37.60
Purchase #3	$89.40	5.527%	$94.3411	$94.34	$94.35	$94.30
Purchase #4	$113.93	4.853%	$119.459	$119.46	$119.45	$119.50
Purchase #5	$42.59	9.599%	$46.6782	$46.68	$46.70	$46.70
Purchase #6	$16.90	9.622%	$18.5261	$18.53	$18.55	$18.50
Purchase #7	$113.81	8.395%	$123.3643	$123.36	$123.35	$123.40
7 purchase totals =	$434.74		$465.8433	$465.84	$465.85	$465.90