What @Brucanna addressed was calculation of depreciation, which Manager does not do. Manager only records purchase costs and depreciation to determine book value. His comment about depreciating groups refers to grouping assets of similar type and depreciation schedule to perform common calculations. In Manager, you cannot actually apply depreciation to a group unless the assets are being treated as a single piece of property.
Your statement that you have hundreds of items per year makes me wonder whether you really need to capitalize all of them. Check local tax laws to see whether they can be expensed. Even if they must be capitalized, you may be able to claim the full value in one year through some accelerated depreciation scheme. Again, check with a local accountant about this. But if you can, see this Guide: