You can do it in a similar way in Qlikview. You can create a table in this format
FromCurrency, ToCurrency, ConversionRate
Where FromCurrency :- Transaction Currency (make a join in qlikview by giving a common alias)
ToCurrency :- The Currency in which u wish to see the values
ConversionRate :- the conversionrate from From to To Currency.
Give a selection of ToCurrency to the use , so a use can select a value at any moment. Select a single value & in List properties select the property "Always one value selected" so a user is able to see the values in only a single currencies at a time & put a formula like Sales Amount * ConversionRate .