There are many compilations for grade 3-5 cello readily available with various types of music.
There is the Time Pieces for Cello collection by ABRSM Publishing, Both volume 2 and 3 contain pieces to the standard of grade 3-5 and are fun to play through
If you want more jazz-type music Play Gershwin published by Faber Music includes a lot of famous compositions by Gershwin and includes a grade 4 and a grade 5 piece (Grade 4: Lets Call the Whole Thing Off, Grade 5: Summertime)
Classic Experience Encores is also a very helpful book filled with excellent pieces and to my knowledge contains various grade pieces, I know there is a Grade 5 piece being Sleeping Beauty Waltz by Tchaikovsky. This is published by Cramer Music.
All 4 of these books are excellent and are quite good for the price (gerswin being the dearest at only Â£7.50) and the others costing Â£5.25 for one of the time pieces books and Â£5.50 for Classic Experience Encores.#
I hope I've been able to help