How to Kepp same value for Friday to Friday

I would do this in Power Query.
Use the Table.ReplaceValue function to set any non-Friday date total to null and then use the Table.FillDown function to fill in the nulls with the previous Friday value. Of course this assumes the table is sorted. 
Here is a sample code you can play with.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Zc9BCsMwDETRu2gdiDSOJfksJve/RounjVu0MzyE/8wpJofYaX5C4e83hqrcxxQQ4oHMvqARckPw4iKMB8IJfQF0X3SCE+znj1wQBGxovEhC+0LTT+4gXCXXlNJLr3E7vAQbxyNKsXE9siQb52P8N98v", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [NO = _t, Date = _t, Total = _t]),
    intial_type_set = Table.TransformColumnTypes(Source,{{"NO", Int64.Type}, {"Date", type date}}),
    replace_non_fridays = Table.ReplaceValue(intial_type_set,each [Total],each if Date.DayOfWeekName([Date]) = "Friday" then [Total] else null,Replacer.ReplaceValue,{"Total"}),
    fill_down = Table.FillDown(replace_non_fridays,{"Total"}),
    set_total_type = Table.TransformColumnTypes(fill_down,{{"Total", Int64.Type}})
in
    set_total_type

Please try the formula below:

Friday Total =
VAR _CurrentDate =
    MAX ( DimDate[Date] )

VAR _LastFriday =
    CALCULATE (
        MAX ( DimDate[Date] ),
        FILTER (
            ALL ( DimDate ),
            DimDate[Date] <= _CurrentDate
                && WEEKDAY ( DimDate[Date], 2 ) = 5
        )
    )
RETURN
CALCULATE (
    SUM ( Fact[Total] ),
    DimDate[Date] = _LastFriday
)

damit230183 

you can try this to create a column

Column =

var _date=maxx(FILTER('Table','Table'[date]<=EARLIER('Table'[date])&&weekday('Table'[date],1)=6),'Table'[date])

return maxx(FILTER('Table','Table'[date]=_date),'Table'[Total])

 

 

pls see the attachment below