新蛋是在退貨流程與說明有提到。
http://www.newegg.com.tw/MyService/Return_goods

依照消費者保護法之規定，於台灣新蛋網購物的會員，可享有商品貨到次日起七天猶豫期的權益。但猶豫期並非試用期，所以，您所退回的商品必須是全新的狀態(不得有刮傷、破損、受潮)，而且完整包裝內容的完整性（包含商品本體、配件、原廠包裝、保護袋、保麗龍、保證書、隨附文件、贈品等）。如欲在七天猶豫期間退貨，須注意商品仍維持完整性，且付擔部份拆裝/整新費用，其費用為商品售價的25%為最高上限。會員若是購買CPU處理器、主機板、顯示卡等商品，彩盒一經毀損，僅接受換貨，不接受退貨。

不過美國新蛋只收 15%
http://www.newegg.com/HelpInfo/FAQDetail.aspx?Module=6
Any return for a refund may be subject to a 15% restocking fee. This fee may be waived for the following reasons:

Carrier damage
Defective product
Product does not match advertising
Received incorrect product
Product was an extra item not ordered

Note: Any return that is misrepresented as being for any of the above reasons will automatically have the restocking fee applied even if it was initially waived.