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	$158.39	7.250%	$169.8733	$169.87	$169.85	$169.90
Purchase #2	$12.86	7.561%	$13.8323	$13.83	$13.85	$13.80
Purchase #3	$74.58	10.692%	$82.5541	$82.55	$82.55	$82.60
Purchase #4	$119.33	4.455%	$124.6462	$124.65	$124.65	$124.60
Purchase #5	$169.50	10.124%	$186.6602	$186.66	$186.65	$186.70
Purchase #6	$143.59	10.598%	$158.8077	$158.81	$158.80	$158.80
Purchase #7	$159.29	5.556%	$168.1402	$168.14	$168.15	$168.10
7 purchase totals =	$837.54		$904.5140	$904.51	$904.50	$904.50