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	$79.41	8.218%	$85.9359	$85.94	$85.95	$85.90
Purchase #2	$193.40	9.240%	$211.2702	$211.27	$211.25	$211.30
Purchase #3	$238.33	10.309%	$262.8994	$262.90	$262.90	$262.90
Purchase #4	$8.51	11.295%	$9.4712	$9.47	$9.45	$9.50
Purchase #5	$91.59	9.455%	$100.2498	$100.25	$100.25	$100.20
Purchase #6	$132.98	9.656%	$145.8205	$145.82	$145.80	$145.80
Purchase #7	$43.49	7.690%	$46.8344	$46.83	$46.85	$46.80
7 purchase totals =	$787.71		$862.4814	$862.48	$862.45	$862.40