Konwertuj ciąg na szeroki ciąg
https://www.cplusplus.com/reference/string/to_wstring/
_rtSales = 1209.15;
CStringW wsTsales;
wsTsales.Format(L"%f", _rtSales);
PointF pointF6(475.0f, 350.0f);
graphics.DrawString(L"Sales", -1, &font2, pointF6, &solidBrush);
PointF pointF6b(700.0f, 350.0f);
graphics.DrawString(wsTsales, -1, &font2, pointF6b, &solidBrush);
Filthy Falcon