a bit ineficiant but so you can see how it works
make a text input field
and a text (output)box
then
+ System: len(tokenat(TextInput.Text, 1, ".")) = 0
(This counts the characters after the decimal and checks if = 0)
-> Text: Set text to tokenat(TextInput.Text, 0, ".")&"."&tokenat(TextInput.Text, 1, ".")&"000"
(If true then this sets the text to the characters before the decimal + a decimal point + 000)
Then just repeat for 1 2 3 i.e more characters after decimal less 0s
+ System: len(tokenat(TextInput.Text, 1, ".")) = 1
-> Text: Set text to tokenat(TextInput.Text, 0, ".")&"."&tokenat(TextInput.Text, 1, ".")&"00"
+ System: len(tokenat(TextInput.Text, 1, ".")) = 2
-> Text: Set text to tokenat(TextInput.Text, 0, ".")&"."&tokenat(TextInput.Text, 1, ".")&"0"
+ System: len(tokenat(TextInput.Text, 1, ".")) = 3
-> Text: Set text to tokenat(TextInput.Text, 0, ".")&"."&tokenat(TextInput.Text, 1, ".")