I found another solution.
In booster for Woocommerce, in Prices¤cies there are options for defining currency symbols (text only unfortunately, no graphics) and price formats.
If I use USD symbol instead of $ – all GTtranslate translations work as intended.
It seems that $ sign is maliciously and recklessly translated into other currency symbols by Gtranslate, but official currency symbols such as USD or JPY are left alone.
I tried to notify GTtranslate using chats and emails, but they redirected my to this forum. Can anyone tell Google to stop translating $ symbol into other currency symbols???