I’m guessing your using a ordered datastore because your allowed doubles in normal datastore
What you can do is
local value = 103.245643664
value = math.round(value * 1000)
-- now save value to datastore
-- and once you load the value from datastore
value /= 1000
print(value) -- 103.245
Instead of 1000 you can use larger values like 10000 or 100000 to save more decimals