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	$90.75	5.581%	$95.8148	$95.81	$95.80	$95.80
Purchase #2	$90.79	5.459%	$95.7462	$95.75	$95.75	$95.70
Purchase #3	$104.94	4.509%	$109.6717	$109.67	$109.65	$109.70
Purchase #4	$167.81	3.162%	$173.1162	$173.12	$173.10	$173.10
Purchase #5	$167.98	11.659%	$187.5648	$187.56	$187.55	$187.60
Purchase #6	$118.91	3.734%	$123.3501	$123.35	$123.35	$123.40
Purchase #7	$216.94	6.759%	$231.603	$231.60	$231.60	$231.60
7 purchase totals =	$958.12		$1,016.8668	$1,016.86	$1,016.80	$1,016.90