I... I don't really think that helps me
I don't need to know the current price for any reason.
Surely this sorta thing is commonly done though, for other assets/investments.. Maybe it's just elementary spreadsheet stuff but I just can't get my head around spreadsheets, they're too damn boring.
say you want to sell 5% every time the price doubles.
row 1 put this stuff
column a - [current BTC holding]
column b - [A1*0.05]
column c - [current BTC price]
row 2 put this
column a - [A1-B1]
column b - [A2*0.05]
column c - [C1*2]
copy row 2 and paste it into the next 20 rows or so, it should automagically adjust formulas.
your spreadsheet then shows
column1 - remaining bitcoin
column2 - your target sell amount in BTC
column3 - your target sell price in BTC
tweak the multipliers, tweak the percentage, until you like what you see
if you can't do spreadsheets, then try pencil, paper and a calculator. thats how it was done before spreadsheets were invented
if you think that sounds like a pain in the ass, it is, thats why you learn spreadsheets