sub-total every 8 records

[mdemarte]

Is it possible to sub-total every 8 records? For example, if the field is Invitemtotal and their are 10 records to list, I would need a sub-total for the first 8, then the 2 that are left, and finally a grand-total. Records are grouped by vendor#, which is where I Sum(Invitemtotal) for the grand-total.