Allow to round taxes on order-level (#5019)

* Allow to round taxes on order-level

* Rename get_cart_total

* Persist rounding mode with order

* Add general docs

* Order creation API

* Update fee algorithm

* Rounding on payment method change

* Round when splitting order

* Fix failing tests

* Add settings page

* Add tests

* Replace algorithm

* Add test case for currency rounding

* Improve order change

* Update flowchart

* Update discount logic (more hypothetical, we don't store rounding on cart positions atm)

* Rename internal method

* Fix typo

* Update help text

* Apply suggestions from code review

Co-authored-by: luelista <weller@rami.io>

* Order rounding refactor (#5571)

* Add RoundingCorrectionMixin providing before-rounding-values as properties

* Use gross_price_before_rounding in more places

* Update doc/development/algorithms/pricing.rst

Co-authored-by: Martin Gross <gross@rami.io>

* Allow to override on perform_order

* Rebase migration

* Fix event cancellation

---------

Co-authored-by: luelista <weller@rami.io>
Co-authored-by: Martin Gross <gross@rami.io>

src/pretix/control/views/event.py

@@ -54,7 +54,7 @@ from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import PermissionDenied
 from django.core.files import File
 from django.db import transaction
-from django.db.models import ProtectedError
+from django.db.models import Count, ProtectedError
 from django.forms import inlineformset_factory
 from django.http import (
     Http404, HttpResponse, HttpResponseBadRequest, HttpResponseNotAllowed,
@@ -90,7 +90,7 @@ from pretix.control.forms.event import (
     EventFooterLinkFormset, EventMetaValueForm, EventSettingsForm,
     EventUpdateForm, InvoiceSettingsForm, ItemMetaPropertyForm,
     MailSettingsForm, PaymentSettingsForm, ProviderForm, QuickSetupForm,
-    QuickSetupProductFormSet, TaxRuleForm, TaxRuleLineFormSet,
+    QuickSetupProductFormSet, TaxRuleForm, TaxRuleLineFormSet, TaxSettingsForm,
     TicketSettingsForm, WidgetCodeForm,
 )
 from pretix.control.permissions import EventPermissionRequiredMixin
@@ -648,6 +648,25 @@ class PaymentSettings(EventSettingsViewMixin, EventSettingsFormView):
         return context
 
 
+class TaxSettings(EventSettingsViewMixin, EventSettingsFormView):
+    template_name = 'pretixcontrol/event/tax.html'
+    form_class = TaxSettingsForm
+    permission = 'can_change_event_settings'
+
+    def get_success_url(self) -> str:
+        return reverse('control:event.settings.tax', kwargs={
+            'organizer': self.request.organizer.slug,
+            'event': self.request.event.slug,
+        })
+
+    def get_context_data(self, *args, **kwargs) -> dict:
+        context = super().get_context_data(*args, **kwargs)
+        context['taxrules'] = self.request.event.tax_rules.annotate(
+            c_items=Count("item")
+        ).all()
+        return context
+
+
 class InvoiceSettings(EventSettingsViewMixin, EventSettingsFormView):
     model = Event
     form_class = InvoiceSettingsForm
@@ -1263,16 +1282,6 @@ class EventComment(EventPermissionRequiredMixin, View):
         })
 
 
-class TaxList(EventSettingsViewMixin, EventPermissionRequiredMixin, PaginationMixin, ListView):
-    model = TaxRule
-    context_object_name = 'taxrules'
-    template_name = 'pretixcontrol/event/tax_index.html'
-    permission = 'can_change_event_settings'
-
-    def get_queryset(self):
-        return self.request.event.tax_rules.all()
-
-
 class TaxCreate(EventSettingsViewMixin, EventPermissionRequiredMixin, CreateView):
     model = TaxRule
     form_class = TaxRuleForm