run this code :
 @Override
    public void start(Stage primaryStage) {
        XYChart chart = new LineChart(new NumberAxis(0, 5, 1), new NumberAxis(0,5, 1));
        chart.getXAxis().setStyle("-fx-minor-tick-count:2");
        StackPane root = new StackPane();
        root.getChildren().add(chart);
        Scene scene = new Scene(root, 300, 250);
        primaryStage.setTitle(VersionInfo.getRuntimeVersion());
        primaryStage.setScene(scene);
        primaryStage.show();
    }

output :
WARNING: com.sun.javafx.css.StyleHelper transitionToState Failed to set css [StyleableProperty {property: -fx-minor-tick-count, converter: SizeConverter, initalValue: 5, inherits: false, subProperties: []}]

java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.Integer
at com.sun.javafx.css.StyleableIntegerProperty.applyStyle(StyleableIntegerProperty.java:31)
at com.sun.javafx.css.StyleableProperty.set(StyleableProperty.java:70)
at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:848)
at javafx.scene.Node.impl_processCSS(Node.java:7324)
at javafx.scene.Parent.impl_processCSS(Parent.java:1146)
at javafx.scene.Parent.impl_processCSS(Parent.java:1153)
at javafx.scene.Parent.impl_processCSS(Parent.java:1153)
at javafx.scene.Parent.impl_processCSS(Parent.java:1153)
at javafx.scene.Node.processCSS(Node.java:7292)
at javafx.scene.Scene.doCSSPass(Scene.java:444)
at javafx.scene.Scene.preferredSize(Scene.java:1411)
at javafx.scene.Scene.impl_preferredSize(Scene.java:1478)
at javafx.stage.Window$10.invalidated(Window.java:719)
at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:127)
at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:161)
at javafx.stage.Window.setShowing(Window.java:782)
at javafx.stage.Window.show(Window.java:797)
at javafx.stage.Stage.show(Stage.java:229)
at javafxapplication1.JavaApplication2.start(JavaApplication2.java:35)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:319)
at com.sun.javafx.application.PlatformImpl$5.run(PlatformImpl.java:206)
at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:173)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:76)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication$3$1.run(GtkApplication.java:82)
at java.lang.Thread.run(Thread.java:722)