The boundary with 100 does, indeed represent a challenge. However we choose to resolve this particular challenge (I would vote for yes, it's a 3-digit precision, so 105 MUST be rendered as 1.1 x 10^2), the sig figs use in multi-step computation is simple: carry one extra digit without round-off (truncate) in all intermediate steps, and round-off at the end.
What we need is a custom answer checker, or an additional method overlaid on the main one.
Something along the lines of this method.
multianswer and original_student_ans
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