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	$60.27	5.419%	$63.536	$63.54	$63.55	$63.50
Purchase #2	$198.38	5.113%	$208.5232	$208.52	$208.50	$208.50
Purchase #3	$151.41	5.242%	$159.3469	$159.35	$159.35	$159.30
Purchase #4	$172.32	5.128%	$181.1566	$181.16	$181.15	$181.20
Purchase #5	$214.73	12.808%	$242.2326	$242.23	$242.25	$242.20
Purchase #6	$154.86	8.660%	$168.2709	$168.27	$168.25	$168.30
Purchase #7	$52.77	10.838%	$58.4892	$58.49	$58.50	$58.50
7 purchase totals =	$1,004.74		$1,081.5554	$1,081.56	$1,081.55	$1,081.50