It's pretty simple as it stands, but you could make it a bit less redundant mainly by getting the elements text only once and reusing the variable:
var text = $('.taxclass').text();
if (text.indexOf(tax1)>-1 || text.indexOf(tax2)>-1) {
}
A further note could be to reduce the traversal of the DOM by using an identifier and looking only for a distinct element (if that suits your needs) instead of every possible thing that has the class taxclass
.