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	$217.51	7.585%	$234.0081	$234.01	$234.00	$234.00
Purchase #2	$145.85	5.150%	$153.3613	$153.36	$153.35	$153.40
Purchase #3	$134.76	5.726%	$142.4764	$142.48	$142.50	$142.50
Purchase #4	$63.82	13.391%	$72.3661	$72.37	$72.35	$72.40
Purchase #5	$85.78	11.425%	$95.5804	$95.58	$95.60	$95.60
Purchase #6	$118.79	8.429%	$128.8028	$128.80	$128.80	$128.80
Purchase #7	$173.83	5.679%	$183.7018	$183.70	$183.70	$183.70
7 purchase totals =	$940.34		$1,010.2969	$1,010.30	$1,010.30	$1,010.40