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	$196.56	9.561%	$215.3531	$215.35	$215.35	$215.40
Purchase #2	$79.59	9.796%	$87.3866	$87.39	$87.40	$87.40
Purchase #3	$38.60	4.773%	$40.4424	$40.44	$40.45	$40.40
Purchase #4	$228.81	11.871%	$255.972	$255.97	$255.95	$256.00
Purchase #5	$203.27	10.661%	$224.9406	$224.94	$224.95	$224.90
Purchase #6	$236.46	8.365%	$256.2399	$256.24	$256.25	$256.20
Purchase #7	$129.59	5.123%	$136.2289	$136.23	$136.25	$136.20
7 purchase totals =	$1,112.88		$1,216.5635	$1,216.56	$1,216.60	$1,216.50