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	$92.38	11.630%	$103.1238	$103.12	$103.10	$103.10
Purchase #2	$79.45	7.134%	$85.118	$85.12	$85.10	$85.10
Purchase #3	$31.68	10.130%	$34.8892	$34.89	$34.90	$34.90
Purchase #4	$51.80	5.130%	$54.4573	$54.46	$54.45	$54.50
Purchase #5	$222.61	6.584%	$237.2666	$237.27	$237.25	$237.30
Purchase #6	$131.66	6.501%	$140.2192	$140.22	$140.20	$140.20
Purchase #7	$198.58	7.797%	$214.0633	$214.06	$214.05	$214.10
7 purchase totals =	$808.16		$869.1374	$869.14	$869.05	$869.20