One year later the propability is high you found a solution for your problem but since my previous answer gets downvoted (admittingly righteously) I want to share a more proper solution:
The following script creates a stack of temporary feature layers each for all entries that share the same PropertyID (it's a simple range-loop since the values seem to be just integers). Then it copies from each temporary feature layer the one with the highest PERCENTAGE value ito a new featureclass or whatever is needed:
#this is your Parcel_Test_SpatialJoin_Tabu1:
parcel = arcpy.GetParameterAsText(0)
#returns the maximum value in the field "PERCENTAGE":
cursor = arcpy.SearchCursor(input)
percentlist = 
for row in cursor:
percentages = row.getValue("PERCENTAGE")
#returns a temporary feature lyer resulting of expr:
def sel_n(inputFC, expr, PropertyID):
temp_lyr = "temp_lyr_%s" %(PropertyID)
#list to filled with the desired entries:
max_per_id = 
target = either_a_new_FC_or_a_table
#since the values of "PropertyID" seem to be all integers:
for i in range(insert_the_highest_value_of_PropertyID_here):
expr = "PropertyID = %s" %(i)
arcpy.Append_management (inputs, target, "TEST")
NOTE1: I didn't test this script, I just fiddled it together from what I have since i am currently working on a similar issue.
NOTE2: If you really need ALL values of a selection "PropertyID = X" preserved I suggest to either expand the script with arcpy.Dissolve_Management in the max_percent function or insert the other values you want to keep in seperate fields programmatically. Since I dont know your requirements for your result i cant help you further.
NOTE3: I am sure there might be a less copious approach to this - perhaps even in model builder.
NOTE4: Happy Halloween.