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	$111.27	12.387%	$125.053	$125.05	$125.05	$125.10
Purchase #2	$128.88	9.293%	$140.8568	$140.86	$140.85	$140.90
Purchase #3	$119.65	12.112%	$134.142	$134.14	$134.15	$134.10
Purchase #4	$107.89	3.109%	$111.2443	$111.24	$111.25	$111.20
Purchase #5	$162.65	8.436%	$176.3712	$176.37	$176.35	$176.40
Purchase #6	$230.59	5.389%	$243.0165	$243.02	$243.00	$243.00
Purchase #7	$192.64	11.773%	$215.3195	$215.32	$215.30	$215.30
7 purchase totals =	$1,053.57		$1,146.0033	$1,146.00	$1,145.95	$1,146.00