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	$205.33	9.758%	$225.3661	$225.37	$225.35	$225.40
Purchase #2	$76.43	9.533%	$83.7161	$83.72	$83.70	$83.70
Purchase #3	$42.26	13.786%	$48.086	$48.09	$48.10	$48.10
Purchase #4	$80.99	11.373%	$90.201	$90.20	$90.20	$90.20
Purchase #5	$242.50	4.490%	$253.3883	$253.39	$253.40	$253.40
Purchase #6	$245.54	7.642%	$264.3042	$264.30	$264.30	$264.30
Purchase #7	$45.33	3.151%	$46.7583	$46.76	$46.75	$46.80
7 purchase totals =	$938.38		$1,011.8200	$1,011.83	$1,011.80	$1,011.90