Calculate TAX within Gross Price

Hi all,

We are configuring the purchasing process for Bolívia (non localized country). So we have the following requirement in tax calculation:

IVA Rate: 13%

Invoice Total Amount: 1000 USD

Net Amount: 870 USD

Tax Amount:130 USD

So I need to inform the price 1000 USD, but my pricing procedure calculates 1000 + 130 = 1130 (invoice total amount). If I inform the price 870 my pricing procedure will calculate 870 +113,1 = 983,1 (invoice total amount).

So my requirement is to inform the price 1000 and the procedure deducts the tax amount (IVA) 130 from the amount and my tax calculate procedure calculates 130. Thus, the calculation will be 870 +130 = 1000 (invoice total amount).

Does anyone knows if exist a standard way to do it?

Thanks

Gian