Starting with 11.0, companies can explicitly set a Sales Tax that will display not only on the Proposal but on the ensuing Invoice, once a Proposal is Accepted.  Once the setting is turned on, the administrator will have to select one of the currently available Sales Tax Codes that is used for Invoicing.  If a new Sales Tax Code is needed, then one will have to be created - using the same process as creating Sales Tax Codes for Invoices.  

Once the Sales Tax Setting is activated and the Sales Tax Code is selected, then in the proposal there will be a "Cost Breakdown" section.  This will show the Subtotal of the Proposal, list the Sales Tax Amount and then provide the new "Cash Price" for the Proposal.   This "Cost Breakdown" will appear on both the Proposal Comparison page as well as on the individual option.