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	$94.91	10.586%	$104.9572	$104.96	$104.95	$105.00
Purchase #2	$30.33	7.671%	$32.6566	$32.66	$32.65	$32.70
Purchase #3	$159.52	4.167%	$166.1672	$166.17	$166.15	$166.20
Purchase #4	$233.48	12.587%	$262.8681	$262.87	$262.85	$262.90
Purchase #5	$163.50	5.590%	$172.6397	$172.64	$172.65	$172.60
Purchase #6	$24.82	3.108%	$25.5914	$25.59	$25.60	$25.60
Purchase #7	$249.37	3.213%	$257.3823	$257.38	$257.40	$257.40
7 purchase totals =	$955.93		$1,022.2625	$1,022.27	$1,022.25	$1,022.40