SL taxes on purchase orders and voucher entry

I have gone through the steps of setting up tax id's and tax categories in the shared information module however, I can not get taxes on inventory items to pull onto my purchase orders or into my voucher entry screen. I have taxes allowed in my AP setup and assigned to inventory items. I can see the tax amounts calculated in the voucher entry by clicking the tax button in the lower right corner but do not see them on a line within voucher entry. It is my understanding I should be able to have a new line with tax amount automatically added in my voucher screen but this is not currently happening. 

Is there a way to get taxes to appear as part of my purchase orders? 

Also, can they automatically be added in a separate line in voucher entry? 

Thank you!