You will need to calculate that 2% lot size and store it into a variable before using the corresponding martingale money management. However, will you be doubling lot size as 2%, 4%, 8%? That is too risky.
Final results are:
1-For rounding a variable:
Use code : DoubleToString(variable,2);
2- For finding remainder division
Use code: MathMod(variable1,variable2);
For using codes in block: Use "Value" & "Text(code input)"