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	$86.91	8.616%	$94.3982	$94.40	$94.40	$94.40
Purchase #2	$10.37	6.827%	$11.078	$11.08	$11.10	$11.10
Purchase #3	$57.83	6.506%	$61.5924	$61.59	$61.60	$61.60
Purchase #4	$235.27	4.176%	$245.0949	$245.09	$245.10	$245.10
Purchase #5	$101.42	9.536%	$111.0914	$111.09	$111.10	$111.10
Purchase #6	$12.64	12.347%	$14.2007	$14.20	$14.20	$14.20
Purchase #7	$92.31	3.280%	$95.3378	$95.34	$95.35	$95.30
7 purchase totals =	$596.75		$632.7934	$632.79	$632.85	$632.80