If it is down significantly... that would not seem to be a time to 'take profits'... especially if the value of the business is still good. For example, if XYZ, Inc is selling for 15 dollars per share, and you determine it is worth 20, you should buy it. If the price goes down by 5% (so now you can get a share worth 20 dollars for $14.25), you should BUY MORE...:)
3 to 5% is a rounding error. If I sold everything every time I expect and drop of 3, 5 or even 10% I would give much of may gains to the IRS and end up missing the big moves.
Buy when everyone is in a panic and leave it alone until your outlook for the company changes significantly. I heard a statistic recently that said that there were 10 trading days in the last year that returned most of our gains. Stick with quality companies with diligent management and leave the rest of the junk alone. .... just my 5c!