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	$109.87	8.665%	$119.3902	$119.39	$119.40	$119.40
Purchase #2	$203.61	8.474%	$220.8639	$220.86	$220.85	$220.90
Purchase #3	$32.96	10.539%	$36.4337	$36.43	$36.45	$36.40
Purchase #4	$38.27	13.551%	$43.456	$43.46	$43.45	$43.50
Purchase #5	$227.46	12.821%	$256.6226	$256.62	$256.60	$256.60
Purchase #6	$246.67	6.329%	$262.2817	$262.28	$262.30	$262.30
Purchase #7	$241.60	5.669%	$255.2963	$255.30	$255.30	$255.30
7 purchase totals =	$1,100.44		$1,194.3444	$1,194.34	$1,194.35	$1,194.40