The quantity plugin enables you to configure pricing, and quality differentials per product / category, based on almost any parameter you might require, examples being, percentages, fixed amounts or volume of order. With the version plgvm_istraxx_quantity_vm2.0.20_1.0 and vm2.0.20 or higher you can combine quantities of different products within a category. You can also combine different variants of one product. Example: If you want to sell single products for $10 each but want to sell 100 of the same items / product, for $8.00 each, this can easily be achieved using the iStraxx quantity plugin, you can also adjust prices by percentage per volume and many more possible calculations. The plugin integrates seamlessly into the calculation edit view, and is easy to set up and use.

# Use case
Offer product based discounts within calculation rules
Show product quantity or value discount
Discount on cart product quantity or value

# Config options
Discount range table
Multiple quantity steps for adjustable discount rates
Combine variants, or childs
Consider categories and manufacturer restriction
Show product based discount prices as table on the product detail page

This plugin helps you to easily benefit and enhance the strong calculation rules of VirtueMart, combined with these new options and possible different calculation dependencies, already provided with VirtueMart 2 and 3, you are able to easily set up and increase sales by volume. Easy to set up within VirtueMart calculation rules.

SOME NOTES TO THE VIRTUEMART CALCULATION RULES SYSTEM IN GENERAL
It is quite easy to stumble over the calculation rule system, when you are not used to it. The power of the calculation systems is in its variety of combinations. The most interesting attributes to combine are usually the product categories and the shoppergroups. Consider that you can use unpublished product categories, to layout an hidden structure about your products and to create with it a fine grained calculation.
Lets assume you have a lot different products, from different manufacturers, but mostly of 3 different distributors. Lets assume the quantity discount depends mainly by the category and the distributor. Then add for each distributor a category and set it to unpublished. Then you can add this category to your product. It is not visible in the Frontend, but the rules are working with it.
The same with sizes. Lets assume you sell beer. In germany we have as package size 6, 12, and 20. Of course you like it when the people by “even” numbers. So you can create three rules, combine it with the quantity =6, =12 and, =20 and connect it to a category size6, size12, size20. Add these categories then to your products.

For more information about the rule system please read https://docs.virtuemart.net/manual/17-products-menu/30-taxes-and-calculation-rules.html

INSTALLATION LINK