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	$91.59	10.239%	$100.9679	$100.97	$100.95	$101.00
Purchase #2	$102.27	11.565%	$114.0975	$114.10	$114.10	$114.10
Purchase #3	$199.29	11.834%	$222.874	$222.87	$222.85	$222.90
Purchase #4	$68.45	10.843%	$75.872	$75.87	$75.85	$75.90
Purchase #5	$153.34	6.221%	$162.8793	$162.88	$162.90	$162.90
Purchase #6	$104.79	6.423%	$111.5207	$111.52	$111.50	$111.50
Purchase #7	$227.98	13.493%	$258.7413	$258.74	$258.75	$258.70
7 purchase totals =	$947.71		$1,046.9527	$1,046.95	$1,046.90	$1,047.00