The lines in the pp_confirm.php page are the ones I've already provided.
On the confirm.php page the lines and new code are:
line 50 to:
$WA_PP_ECO_Set_params[1][$nextIndex] = "".number_format($eCart1->GrandTotal(),2) ."";
update line 58 to:
$WA_PP_ECO_Do_itemized[1][$nextIndex] = "".number_format($eCart1->DisplayInfo("Price"),2) ."";
and update line 77 to:
$WA_PP_ECO_Set_params[1][$nextIndex] = "".number_format($eCart1->TotalColumn("TotalPrice"),2) ."";