In minuet in A minor by Johann Krieger, it doesn't have a major 7th going to the octave, but it has the fifth going to the tonic and the tonic playing an octave above on both notes. Is this a common cadence? Are there other cadences without a raised 7th in baroque music? What are the rules to this?
I'm presuming you mean this minuet:
I can't think of any examples off the top of my head, although I have heard this cadence before - it is fairly typical for two voices.
The constraint to two voices means that some part of the the standard perfect cadence is going to be dropped. The linear descent in the descant to the tonic is a topos (a standard formula) of the minor mode during the Baroque, as is the movement by descending fifth/ascending fourth in the bass. (The use of the lower octave of E in the penultimate bar is also typical - it has a centering effect on the tonic.)
The final cadence of the Courante of Froberger's Suite in E minor FbWV 607 (link to a PDF on IMSLP) has a very similar construction, but, as it has more than two voices, it does use the leading tone in the alto (which is a fairly typical voice for it). Krieger doesn't need to state the leading tone outright as he has used it and left it hanging in m.6 and m.22 - the anticipation of the tonic in m.7 and m.23 picks up where the G♯ leaves off. There is a delayed resolution implied here.
As far as your question asks about "other cadences without a raised 7th in baroque music", I would be remiss if I failed to mention the Phrygian Cadence, which was often used at the end of slow movements in minor keys. Although it's typically analyzed as a iv6-V (e.g. Dm/F-E), it can also be thought of as having evolved from a modal ♭vii6-I in the Phrygian Mode (with a Picardy third making the final chord major). In this analysis, the bass descends to the "tonic" by a half-step, forming an upper leading tone, while an upper voice ascends to the "tonic" by a whole step.
Edit: Agreed with Patrx2; didn't fully read his/her response until I finished my answer, which basically is in agreement. I'll leave it for further elaboration for the OP.
From studying counterpoint in the style of Palestrina years ago, this cadence is sufficient. I imagine that it would therefore be sufficient for Baroque as well.
For the lower voice: Although the final note before the cadence in the lower voice is a rising fourth rather than descending fifth, the note previous to this is in fact a falling fifth motion. In this example, I'd consider the 2nd beat E to 1st beat A to be the functional perfect authentic cadence in the bass (the lower E would be considered an "embellishment" in a way).
For the upper voice: It isn't required for the tonic to be approached by the 7th in order to be considered a perfect authentic cadence. Note the raised 7th in the previous bars before the cadence. It appears to me that in the context of the entire passage, the raised 7th has not been resolved, therefore you do (in effect...) have that 7th->tonic resolution at the end.
I've read some places that you don't even need a falling fifth motion in order to have a perfect authentic cadence (as long as you progress from V to I) <-- This I'm not sure about, but if I remember correctly, it is true (rising fourth to tonic in bass, and non-stepwise motion to the tonic in soprano, are both valid for the perfect authentic cadence).