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	$196.55	11.658%	$219.4638	$219.46	$219.45	$219.50
Purchase #2	$132.71	7.412%	$142.5465	$142.55	$142.55	$142.50
Purchase #3	$27.25	7.585%	$29.3169	$29.32	$29.30	$29.30
Purchase #4	$13.47	6.418%	$14.3345	$14.33	$14.35	$14.30
Purchase #5	$215.68	5.377%	$227.2771	$227.28	$227.30	$227.30
Purchase #6	$180.34	10.137%	$198.6211	$198.62	$198.60	$198.60
Purchase #7	$217.89	4.542%	$227.7866	$227.79	$227.80	$227.80
7 purchase totals =	$983.89		$1,059.3465	$1,059.35	$1,059.35	$1,059.30