Can the question type “slider” be answered in decimal?

The current slider in SMART-TRIAL does not directly support decimals or steps. 

There is, however, a workaround that can be applied if you for instance want "0.1, 0.2, 0.3, etc" decimals, set the slider to go from 1-100 (hide the values), and then add a calculated question that divides the slider value by 10.