The perfect tense of a verb describes the perfected action in a sentence. It can be the present perfect, the past perfect, or simply the future perfect, depending on the sentence and the person relating the sentence. Verbs that are changed to the perfect tense often employ have or had in the sentence. In the present perfect sentence for instance, there are two verbs, simply because it is a compound tense.
As for the sentence mentioned, changing it to the perfect tense would mean adding a has or have and changing the verb to the future or the past depending on your preference. The best answer available is that the company has given raises to its employees.