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	$230.94	13.662%	$262.491	$262.49	$262.50	$262.50
Purchase #2	$65.98	9.340%	$72.1425	$72.14	$72.15	$72.10
Purchase #3	$161.94	11.847%	$181.125	$181.13	$181.15	$181.10
Purchase #4	$80.83	4.483%	$84.4536	$84.45	$84.45	$84.50
Purchase #5	$160.48	4.115%	$167.0838	$167.08	$167.10	$167.10
Purchase #6	$55.40	8.523%	$60.1217	$60.12	$60.10	$60.10
Purchase #7	$96.80	9.379%	$105.8789	$105.88	$105.90	$105.90
7 purchase totals =	$852.37		$933.2965	$933.29	$933.35	$933.30