add-custom-currency-and-symbol.php

/**
 * Add Custom currency name and currency symbol.
 */
function wb_add_my_currency( $currencies ) {
	$currencies['ABC'] = __( 'Currency name', 'woocommerce' );
	return $currencies;
}
add_filter( 'woocommerce_currencies', 'wb_add_my_currency' );

/**
 * Add Custom currency symbol.
 */
function wb_add_my_currency_symbol( $currency_symbol, $currency ) {
	switch ( $currency ) {
		case 'ABC':
			$currency_symbol = '$';
			break;
	}
	return $currency_symbol;
}
add_filter( 'woocommerce_currency_symbol', 'wb_add_my_currency_symbol', 10, 2 );