The ItemData property can only store Integers. One option is to multiply the value by 100 when it is stored and obviously divide by 100 when the value is retrieved.

Code:
Option Explicit

Private Sub Form_Load()
    Dim sngValue As Single
    
    sngValue = 1.98
    Combo1.AddItem "A new service"
    Combo1.ItemData(0) = sngValue * 100

    Combo1.ListIndex = 0
End Sub

Private Sub Combo1_Click()
    Label1.Caption = FormatCurrency(Combo1.ItemData(0) / 100, 2)
End Sub