Accounts software for retailers (variable supplier terms)?

Hi,

Does anyone know of a good accounts package that allows the user to set variable supplier terms (Retail client)?

Our client's current system is outdated, but it does allow them to set specific terms so that they maximise early payment discounts, which they find very useful;

• e.g.  supplier invoice issued between 20th Jan and 19th Feb is payable 10th March to get discount

The rest of the requirements are fairly standard and covered by most accounts packages , but

Any help would be appreciated! 

Thanks!