I just buy and sell commands: /buy anvil max /sell anvil max

My config is almost completely default and one store was created /ss p1 shop /ss p2 shop:
economy-plugin:
use-external: true
hook-internal-economy-into-vault: false
starting-player-account-balance: 0.0
web-page:
enable: false
port: 7777
background-color: 8FA685
font-color: F2F2F2
border-color: '091926'
increase-value-color: C8D9B0
decrease-value-color: F2B2A8
highlight-row-color: 8FA685
header-color: '091926'
table-data-color: 314A59
font-size: 12
font: verdana
enable-web-api: false
web-api-path: API
shop:
default-server-shop-account: hyperconomy
default-server-shop-account-initial-balance: 20000000
display-shop-exit-message: true
max-stock-per-item-in-playershops: 100000
max-player-shop-volume: 1000
max-player-shops-per-player: 1
sell-remaining-if-less-than-requested-amount: true
server-shops-have-unlimited-money: false
limit-info-commands-to-shops: false
block-selling-in-creative-mode: false
show-currency-symbol-after-price: false
unlimited-stock-for-static-items: false
require-chest-shops-to-be-in-shop: false
require-transaction-signs-to-be-in-shop: false
send-price-change-notifications-for: anvil,diamond,diamondblock,
language: ruRU
tax:
account: hyperconomy
purchase: 0
initial: 0
static: 0
enchant: 0
sales: 0
dynamic:
enable: false
money-floor: 0
money-cap: 1000000
max-tax-percent: 100
multi-server:
enable: false
remote-server-ip-addresses: 192.168.1.1,3313;192.168.1.1,3314;192.168.1.2,3313;
port: 3313
update-interval: 500
connection-timeout-ms: 2000
sync-shops: true
sync-trade-objects: true
sync-accounts: true
remote-gui:
enable: false
server: false
remote-server-ip: 192.168.1.1
remote-server-port: 3313
listen-port: 3313
connection-timeout-ms: 10000
refresh-rate-ms: 20000
auth-key: cfmp0oqdomad2gon5grg1lo2bp
history:
days-to-save: 7
sql:
use-mysql: false
log-sql-statements: false
mysql-connection:
username: default_username
port: 3306
password: default_password
host: localhost
database: minecraft
updater:
enabled: true
notify-in-game: true
notify-for:
dev-builds: true
beta-builds: true
recommended-builds: true
enable-feature:
shops: true
item-displays: true
chest-shops: true
info-signs: true
composite-items: true
player-shops: true
scrolling-transaction-signs: false
price-history-storage: true
transaction-signs: true
automatic-backups: true
per-shop-permissions: false
price-change-notifications: true
treat-damaged-items-as-equals-to-undamaged-ones: true
debug-mode: false
uuid-support: true
time-effects: false
bank:
max-ownerships-per-player: 3
intervals:
shop-check: 6
save: 24000
enchantment:
classvalue:
wood: 0.1
leather: 0.1
stone: 0.15
chainmail: 0.2
iron: 0.25
gold: 0.1
diamond: 1
bow: 0.25
book: 1

I don't understand what the problem is. I'll be updating the way the money storage works soon if you're referring to rounding issues. To solve rounding issues if that's what you're encountering implement a small tax that discourages endless trading back and forth to exploit pennies.

I would like to see a realistic economy. I do not understand where the money disappears from the economy when they are taxed.

Currently it goes into the "hyperconomy" account. That can be configured with the tax.account config.yml line. In a future update I'll allow the tax account to be configured at a shop level.