Why should we hire you? Because, i believe i have the skills required for this job. I am commited, responsible and a proactive person I am always attentive to detail. I think of myself as a problem solver with the ability to reorganize processes within my department if required to do so. I am keen to learn new things and improve my skills and abilities, learning comes natural to me. Throughout my career i have gained knowledge in several areas, such as, accounting, taxes, costings and budgeting. I would be delighted to join your company as this would allow me to fulfil my potential, put my knowledge to good use and have a positive impact on the results of the company.

Overall very nice! And remember to give specific examples, employers love that. 

Why should we hire you?
Because, i think i have all the skills, required for this job.
I am a commited, responsible, proactive person and always attentive a details.I am able to solve problems and reorganize process in my area.
I always like to be learning new things that improve my skills and I learn fast I am a fast learner. 
In my career i got have (or "have built up my") knowledge in several areas, such as, accouting, taxes, costs and controlling, i will use my knowledge to improve results in your company.