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	$138.35	10.657%	$153.094	$153.09	$153.10	$153.10
Purchase #2	$52.32	4.484%	$54.666	$54.67	$54.65	$54.70
Purchase #3	$8.56	8.808%	$9.314	$9.31	$9.30	$9.30
Purchase #4	$59.87	10.364%	$66.0749	$66.07	$66.05	$66.10
Purchase #5	$172.52	13.753%	$196.2467	$196.25	$196.25	$196.20
Purchase #6	$165.96	5.488%	$175.0679	$175.07	$175.05	$175.10
Purchase #7	$199.88	10.805%	$221.477	$221.48	$221.50	$221.50
7 purchase totals =	$797.46		$875.9405	$875.94	$875.90	$876.00