Price Rules in Retail have no effect on pricing in eCom. eCom offers Discount Codes and Discount Rules modules for creating timed sales events. For more information, refer to the following eCom help articles:
Considerations regarding discounts
Sales will be pushed from eCom to Retail using the discounted price for all products in the sale. Retail's view of the sale will not show that a discount was applied. The product prices in the sale will simply be lower than usual.
Reporting on eCom sales within Retail will not show that discounts were applied. Instead, the report will just show the discounted price. The margin will still be correctly calculated since the margin is calculated from the price paid and cost of the product.