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	$246.68	6.588%	$262.9313	$262.93	$262.95	$262.90
Purchase #2	$10.83	6.868%	$11.5738	$11.57	$11.55	$11.60
Purchase #3	$132.75	4.797%	$139.118	$139.12	$139.10	$139.10
Purchase #4	$54.95	7.694%	$59.1779	$59.18	$59.20	$59.20
Purchase #5	$118.38	7.644%	$127.429	$127.43	$127.45	$127.40
Purchase #6	$139.64	4.534%	$145.9713	$145.97	$145.95	$146.00
Purchase #7	$79.86	8.684%	$86.795	$86.80	$86.80	$86.80
7 purchase totals =	$783.09		$832.9963	$833.00	$833.00	$833.00