In English, ‘surely’ and ‘for sure’ are adverbs and ‘sure’ is an adjective:
If you ask, you will surely get a discount.
If you ask, you will get a discount for sure.
If you ask, you are sure to get a discount.
In Singlish, ‘sure’ can be an adverb even without ‘for’, and you would never put the adverb at the end of the sentence; it goes before the verb:
If you ask, you will [for] sure get [a] discount.
