How to set float values for Y Axis

I want to draw a financial chart for Dolar, Euro, Gold ext. 

Values for Y-axis are 2.345 - 2.346 - 2.400 - 2.456 .....

When I set these values graph cant draw these points, draw a straight line because they are so close. Also on Y-axis values are 0-2-4. 

Help please,
