related to https://github.com/telerik/kendo-ui-core/issues/3519
workaround for rounding function is using Custom Functions http://docs.telerik.com/kendo-ui/controls/data-management/spreadsheet/custom-functions

kendo.spreadsheet.defineFunction("ROUND", function (x) {
    return Math.round(x);
}).args([
    ["x", "number"]
]);

Cell cell = new Cell() { Index = 0, Formula = "=ROUND(1.2)", Bold = true, Background = "#fef0cd", Format = "$0" };