Understanding problems with single precision and double precision can get you unstuck. Here is description of the problem all be it from a vb.net perspective.
Visual Studio Magazine Online | On VB: Maximize Comparison Accuracy
Personnaly the biggest problem in Access with single precision fields occurs when you use Sum or Avg in group by queries. The results generally come up with a figure that has some weird significant figures. The solution in this case involves changing the field from single precision to double precision. This will increase the table size by 4bytes*no_of_rows which can prove significant in large tables.