Categorize sales for different accounts

The only way to do this is to use a separate set of items on your wholesale sales, items that use the wholesale accounts.  Of course, that may not be suitable as it might break any number of other features, like item based sales reports.

Hi @info-relaxinsole 

The Income account in the P&L that each Item sale posts to is determined by what you have setup on the Item card. So all sales of the same Item will post to the one GL/P&L Income account. This is to show "what you are selling".

Your question is about "who is buying "( Retail v Wholesalers). Suggest you could setup separate Classes to track sales to Retail customers v Wholesale. Classes can be setup where you allocate the Class ( e.g. Retail) once to the overall Sale transaction or to each line of the invoice ( more data entry required). 

If you do setup a Class for each of the Retail and Wholesale divisions this will track Sales and COS but you can also allocate other direct costs to each Class, e.g. Salespeople salaries and commissions that may be  directly related to the Wholesale business, then store costs, online marketing and e-commerce costs that may relate directly to the Retail division. 

This will allow you to produce separate P&L's for each division and see the true profitability of each over time.  You can also setup budgets by each Class.

It is tempting to think the Retail division is making more margin on each item sale so is more profitable but often the additional costs to sell individual items and ship them can significantly reduce the overall profitability of Retail compared to Wholesale!