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	$235.71	11.147%	$261.9846	$261.98	$262.00	$262.00
Purchase #2	$75.67	12.746%	$85.3149	$85.31	$85.30	$85.30
Purchase #3	$62.31	8.268%	$67.4618	$67.46	$67.45	$67.50
Purchase #4	$140.27	13.196%	$158.78	$158.78	$158.80	$158.80
Purchase #5	$154.86	8.603%	$168.1826	$168.18	$168.20	$168.20
Purchase #6	$74.75	5.359%	$78.7559	$78.76	$78.75	$78.80
Purchase #7	$58.63	12.527%	$65.9746	$65.97	$65.95	$66.00
7 purchase totals =	$802.20		$886.4544	$886.44	$886.45	$886.60