Is there a true translation for the word petty? I have asked many locals and referenced many a websites but have not come up with it. Closest is the standard “XiaoQi” but thats not really even close. Anybody know???
xiaoqi is stingy, petty is expressed as 心胸 狹窄 xinxiong xia zhai (lit. narrow minded) or 氣量小的 qiliangxiaode…but neither is used as often as petty in English, possibly because Chinese people are in general more petty than westerners so it isn’t seen as a fault…(thats just me theorizing mind)
I’d like to encourage posters to add tone numerals or marks, like xiao3qi4, if you know the tones.
I’m unaware of any good all-purpose translation for ‘petty’ that would work well in the same situations as in English. As the bear notes, xiao3qi4 is really only ‘stingy’. 
In many contexts, ji4jiao4 (計較) or xiao3xin1yan3 (小心眼) will work. But I don’t think you should look for ‘exact’ translations of words other than nouns. Context and usage will often spoil your attempts to translate the English into Chinese.
there’s “chuimao qiuci” which is “nit-picking,” might work sometimes. there’s “luo suo” but that implies more of continuous verbal harping on petty matters. I believe people often will say “xiaoqi” for petty, “ta hao xiaoqi, shenme shiqing dou hui jijiao”
The primary meaning of 小氣/小器 xiao3qi4 today is “stingy”, but it can also mean something akin to petty. In the past, petty was the primary meaning although in Taiwan, stingy has taken over to be the primary meaning. In other locales, xiao3qi4 is typically not used to mean stingy.
A list of English translations for xiao3qi4 include: stingy;mean;nigardly;tight-fisted;narrow-minded;petty. As Feiren said, it all depends on context.
How about 小心眼 xaio3 xin1 yan3/yien3 ?