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	$86.27	7.692%	$92.9059	$92.91	$92.90	$92.90
Purchase #2	$21.59	6.564%	$23.0072	$23.01	$23.00	$23.00
Purchase #3	$106.82	9.619%	$117.095	$117.10	$117.10	$117.10
Purchase #4	$143.83	5.791%	$152.1592	$152.16	$152.15	$152.20
Purchase #5	$117.64	8.247%	$127.3418	$127.34	$127.35	$127.30
Purchase #6	$231.79	5.740%	$245.0947	$245.09	$245.10	$245.10
Purchase #7	$233.98	9.734%	$256.7556	$256.76	$256.75	$256.80
7 purchase totals =	$941.92		$1,014.3594	$1,014.37	$1,014.35	$1,014.40