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	$241.65	8.493%	$262.1733	$262.17	$262.15	$262.20
Purchase #2	$66.25	13.699%	$75.3256	$75.33	$75.35	$75.30
Purchase #3	$243.51	5.677%	$257.3341	$257.33	$257.35	$257.30
Purchase #4	$168.93	3.216%	$174.3628	$174.36	$174.35	$174.40
Purchase #5	$65.72	10.509%	$72.6265	$72.63	$72.65	$72.60
Purchase #6	$32.54	13.788%	$37.0266	$37.03	$37.05	$37.00
Purchase #7	$224.69	10.871%	$249.116	$249.12	$249.10	$249.10
7 purchase totals =	$1,043.29		$1,127.9649	$1,127.97	$1,128.00	$1,127.90