SAP

ERP is an abbreviation for Enterprise Resource Planning and means, the techniques and concepts for integrated management of businesses as a whole from the viewpoint of the effective use of management resources to improve the efficiency of enterprise management. ERP systems integrate all the functions and departments within an organization through a common information system
Most common modules for an ERP system are Finance, Manufacturing, Human resources, Procurement, Customer relationship management etc. ERP software can be customized to keep critical business processes. SAP is the worlds largest selling Enterprise Resources Planning (ERP) software system. For implementation of SAP you require ABAB developers and functional consultants. If you want to make career in Technical then you may learn ABAB and do certifications. In case you want to be a functional specialist, you can do one of more functional module certification. SAP professionals are paid above normal developers and Business Analysts. With SAP certifications you can join IT companies or IT department of business enterprises. Major advantage of SAP certification is as follows:
(a) Increased probability to get a decent job
(b) Better salary in comparison to no SAP candidate for same post
(c) Well recognized brand certification adds to reputation
(d) Very good career growth opportunities with experience
(e) Opportunities to travel for SAP implementation
(f) Job in foreign countries
SAP functional modules are as follows:
(a) Human Resource Management (SAP HRM), also known as Human Resource (HR)
(b )Production Planning (SAP PP)
(c) Material Management (SAP MM)
(d) Financial Supply Chain Management (SAP FSCM)
(e) Sales and Distribution (SAP SD)
(f) Project System 'SAP PS'
(g) Financial Accounting and Controlling (SAP FICO)
You may do SAP FICO certification to enhance your employ-ability.

SAP ABAP certification is the entry to a technical career in SAP world. It is a huge advantage if you start a career with SAP at an early stage.
SAP ABAP certification will cost you USD $500. Which is directly taken by the students who are not from India.
If you are in India, you need to go with mandatory training if you are fresher (new to SAP). If you have experience with more than 1 year. You can directly appear for SAP ABAP certification. Most of the time, SAP certification is offered by employer themselves.
If you are opting for SAP ABAP training followed by certification. it will cost you around USD $4500 (~INR 3L)+certification cost of USD $500 (~INR33k)
So total it will cost you USD $5000 (~INR 3.5L) with complete SAP ABAP certification in India with no experience.
I personally recommend you to go with training and certification at one shot as SAP has robust training programs.
You can refer SAP ABAP certification guide to prepare well for your certification. Is not necessary to just pass, however, pass with a better score with SAP ABAP certification may lead you to good career opportunities.
Getting into SAP career is not a smooth ride if you just pass the certification. In-depth knowledge of technical analysis is a must to enjoy good slide into SAP career.

Hi Deepak,
Tally is an accounting package which you may use for your day to to accounting and final accounts whereas SAP comes with bigger roles and application for overall enterprise level tool. SAP has multiple module with a combination of BPM and flows of different area of business.
Comparing SAP with Tally is bit unfair in order to scope and function. If you are from a accounts background and I presume you are new in industry then Tally is a package you need to learn in first place so that you will get to know how a software can help you for day to day accounting work but down the line SAP will help you on higher side for management reports/decisions/ capability and analysis.