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	$214.62	4.856%	$225.0419	$225.04	$225.05	$225.00
Purchase #2	$65.49	11.229%	$72.8439	$72.84	$72.85	$72.80
Purchase #3	$89.98	4.733%	$94.2388	$94.24	$94.25	$94.20
Purchase #4	$69.81	9.525%	$76.4594	$76.46	$76.45	$76.50
Purchase #5	$228.49	12.374%	$256.7634	$256.76	$256.75	$256.80
Purchase #6	$55.96	6.165%	$59.4099	$59.41	$59.40	$59.40
Purchase #7	$238.26	12.318%	$267.6089	$267.61	$267.60	$267.60
7 purchase totals =	$962.61		$1,052.3662	$1,052.36	$1,052.35	$1,052.30