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	$177.84	10.246%	$196.0615	$196.06	$196.05	$196.10
Purchase #2	$247.56	11.766%	$276.6879	$276.69	$276.70	$276.70
Purchase #3	$142.70	10.836%	$158.163	$158.16	$158.15	$158.20
Purchase #4	$41.41	9.247%	$45.2392	$45.24	$45.25	$45.20
Purchase #5	$132.69	5.572%	$140.0835	$140.08	$140.10	$140.10
Purchase #6	$21.69	13.367%	$24.5893	$24.59	$24.60	$24.60
Purchase #7	$164.52	13.661%	$186.9951	$187.00	$187.00	$187.00
7 purchase totals =	$928.41		$1,027.8195	$1,027.82	$1,027.85	$1,027.90