Apostolic Penitentiary, Response to a dubium Concerning the Recitation of the Rosary during Eucharistic Exposition, 8 March 1996.
[...] In grant n. 48 of the Enchiridion Indulgentiarum a plenary indulgence is granted to the faithful that devoutly recite the Marian Rosary (even just the third part of it) in a church or oratory.
From the same quoted text it is clear that in no way may it be excluded from the above-mentioned grant the recitation of the Rosary in front of the Blessed Sacrament, both when reserved in the tabernacle and when exposed, in accordance with the general principle of juridical hermeneutics (nothing is excepted where nothing is distinct).
Furthermore, this practice is praiseworthy because whilst our Lord Jesus Christ truly present is adored, also the most Blessed Virgin Mary is invoked with prayers which are essentially biblical (the Our Father, the Hail Mary in its first part, and the Mystery of salvation).
Therefore, the faithful do an excellent thing in continuing such a pious custom in churches.
Yours faithfully [...]
Fr Luigi De Magistris
Fr Ubaldo M. Tedeschini
Prot. No. 29/96/I, 8 March 1996, Notitiae 34 (1998): 511. http://www.ewtn.com/expert/answers/roseuch.htm