This produced proper results -
Code:
GameTooltip:AddDoubleLine("Friendly Discount", addon:MoneyToString(floor(totalCost * 0.95), true))
GameTooltip:AddDoubleLine("Honored Discount", addon:MoneyToString(floor(totalCost * 0.9), true))
GameTooltip:AddDoubleLine("Revered Discount", addon:MoneyToString(floor(totalCost * 0.85), true))
GameTooltip:AddDoubleLine("Exaulted Discount", addon:MoneyToString(floor(totalCost * 0.8), true))