Depreciation over 5 years: why are the amounts different each year?

Hello, I noticed the following when viewing my depreciations. This applies to all my depreciations, but here is an example.Office chair purchased for £300, to be depreciated over 5 years, entered in Dexxter with a depreciation start date of 01-01-2021. Logically, I would think that Dexxter would then depreciate £60 per year (5 years * £60/year = £300).However, I see the next amounts in the depreciation table: £59.97 (2021); £59.97 (2022); £59.97 (2023); £60.13 (2024); £59.97 (2025).This may be a minor detail, but is there a specific reason why Dexxter does not distribute the amounts evenly over all years? Will the tax authorities not be concerned here? Thank you in advance for your answer.