Real-Life Private Firm Valuation Question ask, she, determine, friend, little

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My friend owns 5% of an LLC (an used car dealership which has done very well over the last 7+ years and has very little or no debt). “Sarah” wants to sell her share to the majority owner (95%) and wants to know how much should she ask for it.
I’m thinking that Sarah should determine the value of the firm as per capitalized cash flow method (Level II Equity, page 546). I have two questions:
1) Is the capitalized cash flow method suitable in this case?
2) If yes, should she ask for a price close to 5% of the value of the firm obtained using the above mentioned method or there is some other rule of thumb?
Any feedback is appreciated. Thank you!