I don't think you should vote to close your own questions just because they are answered. There are very few questions that have a definite answer that will never change, or that cannot be improved upon.
Someone might come in three months, a year, or even later, and become aware of a caveat that nobody knew about in the accepted answer. Maybe there was a flaw in the approach and it was discovered later. Maybe it doesn't work anymore because Windows version X doesn't support feature Y anymore. Maybe the question was about Internet Explorer 10 and the correct answer changes for Internet Explorer 11. Maybe you asked the question in regards to today's modern browsers, but the answer doesn't work in the as-yet-unreleased super-duper-browser that will dominate the market in 3 years.
The way I look at it, these questions and answers are not just for you, but for anyone who might have the same question in the future. Just because an answer works for you now doesn't necessarily mean it will work for someone else in the future. By letting the question remain open, you give the chance for other people to contribute an even better answer later.
Also, closure usually implies that there is something wrong with the post, e.g. it does not meet the guidelines for an on-topic question today.
The only reasons why you should vote to close your own questions are:
- Your question has been asked in a different post which has a better answer (in this case, vote or flag your question as a duplicate, then approve it).
- Your question meets the criteria for closure for any other reason, even if it was OK at the time it was posted.
If your question starts to attract bad answers and/or trolling, that is not a reason for closure. Instead, flag your question for moderator attention and ask that it be protected or locked.