changing the increment for a custom resize tool?

I am having trouble changing the increment for a resize tool I adapted for my project.

local tool = script.Parent
local plr = game.Players.LocalPlayer
local mouse = plr:GetMouse()
enabled = true
local selectionBox
local selectionLasso
local handles
local previousDistance
local originalpart
local buttonupconnection
local tempart

function onHandlesDown(normal)
    previousDistance = 0
end



function onHandlesDrag(normal, distance)
    if handles.Adornee then
        local delta = distance - previousDistance
        if math.abs(delta) >= handles.Adornee.ResizeIncrement then
            local sizeDelta = math.floor(delta / handles.Adornee.ResizeIncrement + 0.5) * handles.Adornee.ResizeIncrement
            if handles.Adornee:Resize(normal, sizeDelta) then
                previousDistance = distance
                --send changes to server
                buttonupconnection = mouse.Button1Up:connect(function()onButton1Up(mouse,handles.Adornee)end)
    --
            end
        end
    end
end




function onButton1Up(mouse,part)
    if part and script.Parent.Parent == plr.Character then
    local size = part.Size
    local cfr = part.CFrame
    script.Parent.PartChange:FireServer(originalpart,size,cfr)
    end
end




function onButton1Down(mouse)
    local findpart = game.ReplicatedStorage.BuildingParts:FindFirstChild(mouse.Target.Name)
    if tempart then
        tempart:Destroy()
        end
    if mouse.Target == nil or mouse.Target.Locked or not findpart then
        print("nil")
        selectionBox.Adornee = nil
        selectionLasso.Part = nil
        handles.Adornee = nil
    else
        print("not nil")
        originalpart = mouse.Target
        tempart = findpart:Clone()
        tempart.CanCollide = false
        tempart.Anchored = true
        tempart.Transparency = 0.6
        tempart.Size = originalpart.Size
        tempart.Parent = game.Workspace
        tempart.CFrame = originalpart.CFrame
        tempart.BrickColor = BrickColor.new("Lime green")
        selectionBox.Adornee = tempart
        selectionLasso.Part = tempart
        handles.Adornee = tempart
        handles.Faces = tempart.ResizeableFaces
    end
end




function onEquippedLocal(mouse)
    mouse.Button1Down:connect(function() onButton1Down(mouse) end)

    local character = script.Parent.Parent
    local player = game.Players:GetPlayerFromCharacter(character)

    selectionBox = Instance.new("SelectionBox")
    selectionBox.Color = BrickColor.Blue()
    selectionBox.Adornee = nil
    selectionBox.Parent = player.PlayerGui

    selectionLasso = Instance.new("SelectionPartLasso")
    selectionLasso.Name = "Model Delete Lasso"
    selectionLasso.Humanoid = character.Humanoid
    selectionLasso.Parent = game.workspace
    selectionLasso.Part = nil
    selectionLasso.Visible = true
    selectionLasso.archivable = false
    selectionLasso.Color = BrickColor.Red()

    handles = Instance.new("Handles")
    handles.Color = BrickColor.Blue()
    handles.Adornee = nil
    handles.MouseDrag:connect(onHandlesDrag)
    handles.MouseButton1Down:connect(onHandlesDown)
    handles.Parent = player.PlayerGui
end

function onUnequippedLocal()
    selectionBox:Destroy()
    selectionLasso:Destroy()
    handles:Destroy()
    if handles.Adornee then
        handles.Adornee:Destroy()
    end
    if buttonupconnection then
    buttonupconnection:Disconnect()
    end
end


tool.Equipped:connect(onEquippedLocal)
tool.Unequipped:connect(onUnequippedLocal)

the current function that I am concerned about is onhandlesdrag. I tried changing various things such as handles.adornee.sizeincrement. I tried changing sizedelta up but that didnt work.

I want to change the increment to 0.5, but any attempts that didn't end in failure only ended in the part resizing 1 stud.