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	$172.93	8.626%	$187.8469	$187.85	$187.85	$187.80
Purchase #2	$149.71	8.604%	$162.591	$162.59	$162.60	$162.60
Purchase #3	$211.31	6.797%	$225.6727	$225.67	$225.65	$225.70
Purchase #4	$85.72	5.856%	$90.7398	$90.74	$90.75	$90.70
Purchase #5	$214.84	10.346%	$237.0673	$237.07	$237.05	$237.10
Purchase #6	$156.90	6.151%	$166.5509	$166.55	$166.55	$166.60
Purchase #7	$48.80	11.598%	$54.4598	$54.46	$54.45	$54.50
7 purchase totals =	$1,040.21		$1,124.9284	$1,124.93	$1,124.90	$1,125.00