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	$84.65	12.319%	$95.078	$95.08	$95.10	$95.10
Purchase #2	$125.61	11.135%	$139.5967	$139.60	$139.60	$139.60
Purchase #3	$140.49	3.800%	$145.8286	$145.83	$145.85	$145.80
Purchase #4	$137.38	9.196%	$150.0135	$150.01	$150.00	$150.00
Purchase #5	$226.67	13.119%	$256.4068	$256.41	$256.40	$256.40
Purchase #6	$51.45	12.371%	$57.8149	$57.81	$57.80	$57.80
Purchase #7	$158.95	9.720%	$174.3999	$174.40	$174.40	$174.40
7 purchase totals =	$925.20		$1,019.1384	$1,019.14	$1,019.15	$1,019.10