Asterisk A2Billing Rates uploading- Calculating Hidden charge

Hi need some one to work out the rate sheets to calculate hidden charges on the sheets (rate sheets from sip termination) and show me + explain how to add hidden charges using the rate sheets in excel rather than adding hidden charges using A2Billing platform. Once the rate sheets is set up using the hidden charges then that needs to be imported on A2Billing by selecting the right options. I will be needing three different rates sheets using three different hidden charges. I have rate sheets but just need to be updated with the hidden charges. Person with the IN DEPTH KNOWLEDGE OF CALCULATING HIDDEN CHARGES , CALULALATING HOW MANY MINUTES THE CALLER WILL GET AFTER ADDING THE HIDDEN CHARGES MUST BID. THERE IS NO CONFIGURATION REQUIRED I BELIEVE. PLEASE SEE BELOW THE HIDDEN CHARGES I WANT TO ADD IN THE RATE SHEETS IN EXCEL ========================== 1. "Prices correct as at 11/04/2012 and are subject to change without notice All call charges rounded up to the next 5 cents All calls are charged in blocks of 10 minute/s. Minimum charge of 5 minute/s. Calls to satellite mobiles, special numbers and premium services charged at higher rates or blocked Calls from mobiles may incur an additional fee from your mobile service provider Card expires 3 months from first use or 6 months from last recharge All calls incur a 43.48c surcharge after 5 Minutes, except those marked with a * which incur a 86.96c surcharge after 5 Minutes All calls incur a $1.304 surcharge applied after 2 Minute/s " --------------------- ANOTHER RATE SHEETS WITH 1. TWO MINUTE ROUNDING 2. ALL CALLS WILL BE CHARGE NEAREST TO 5 CENTS ----------------------------- I KNOW THIS WILL NOT TAKE TOO LONG, IMAY TAKE MAXIMUM OF TWO HOURS EVEN LESS IN CALCULATION, EXPLAINING AND SELECTING THE RIGHT CATEGORY THANK YOU