DI API SAP business one how do I overwrite tax on AR Service Invoice line

want to be able to overwrite the tax amount for a AR Invoice ( service type) but also want to specify the tax code and the Line total before tax. My intention is to avert any rounding differences between the source data ( excel) and SAP

in my DI API code I have this ( roughly ) below however it does not take the overwritten value that I specify.

oAPInvoice.Lines.Price = 9.55; //unit price before tax

oAPInvoice.Lines.LineTotal = 9.55 ; //Line total before tax

oAPInvoice.Lines.VatGroup = "S1" ;

// this one actually calculates to 0.955 and SAP would by default round up to 0.96 but my source data is 0.95 so I //want to specify the 0.95. However I end up with 0.96 which means Business One has ignored the line below.

oAPInvoice.Lines.TaxTotal = 0.95 ;