Do you treat the sales tax of your operating expense items (such as office supplies, promotion, etc) sparate from the expenses and post to sales tax?

We use SAP and the IT is working to configure the expense PO in SAP. They ask to code sales tax of the expenses PO as sales tax. My previous experience, we post purchase amount including sales tax under the specific expense item: For example, I purchase a rim of paper at $5+sales tax .4=5.4. I post $5.4 for office supplies. The IT ask to post $5 to office supplies and .4 to sales tax. I didn't see the value to do so and believe this will increase triple work load. What is the best practice? Do you have a sales tax as one of operating expense in your chart of account? Love to hear what you guys think.