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	$199.55	12.233%	$223.961	$223.96	$223.95	$224.00
Purchase #2	$166.76	3.664%	$172.8701	$172.87	$172.85	$172.90
Purchase #3	$107.64	12.753%	$121.3673	$121.37	$121.35	$121.40
Purchase #4	$187.56	6.396%	$199.5563	$199.56	$199.55	$199.60
Purchase #5	$81.35	11.112%	$90.3896	$90.39	$90.40	$90.40
Purchase #6	$214.39	4.832%	$224.7493	$224.75	$224.75	$224.70
Purchase #7	$13.82	12.112%	$15.4939	$15.49	$15.50	$15.50
7 purchase totals =	$971.07		$1,048.3875	$1,048.39	$1,048.35	$1,048.50