[Purchasing from the Agricultural Bank]

The answer—and Allah is the granter of success: What appears regarding that practice is prohibition, for it is the form of usury. A believer ought to avoid it and not enter into it. In the report [it is said], “Believers pause at doubtful matters,” and, “Leave what makes you doubt for what does not make you doubt,” in addition to the safety and precaution gained by refraining from entering into that.
If it is said: The cause for the prohibition of usury is that it entails consuming people’s wealth wrongfully and involves injustice. Allah said, in the context of the verses of usury: “But if you repent, you may have your principal—you do no wrong, nor are you wronged.” [Al-Baqarah:279]. If the matter is as mentioned in the question, then there is no injustice and no excess—unless the “interest” exceeds the item’s true price. If it is less than that, then there is no injustice; accordingly, the sale would be permissible for both buyer and seller.
We say: Usury is a grave sin, and its standing with Allah is great. Hence He, Exalted, says in His Book, threatening the people of usury: “But if you do not, then be informed of a war from Allah and His Messenger.” [Al-Baqarah:279]. A sin of such magnitude must be kept far away from—one must take maximum precautions against it. “Whoever grazes near the sanctuary is liable to fall into it.” The form of usury suffices to deter a Muslim from entering into it or approaching it.
Yes—seller and buyer can avoid the form of usury by changing the form of the contract: the two parties add the expected “interest” on the item to the item’s price, then conclude the sale on that combined amount and make all of it the item’s price. If they do that, there is no problem in the permissibility of that sale, since it then contains neither the form of usury nor its meaning.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2