Shopping

Færsla - book keeping, entry, record
Lýsing - description, lighting, illumination
Afsláttur - discount
Tilboð - offer, bid, tender
Sem - as, as if
Inneign - credit balance
Nóta - note, bill, receipt
Þökk - thanks
Flokka - grade, sort, classify into groups
Vöruflokkar - product categories
Virði - value, worth
Auka - increase
Skattur - tax
VSK (short for Virðisaukaskattur) - Value Added Tax (VAT), a type of sales tax.

Gildir ekki sem inneignarnóta (Not valid as credit)
Þökkum viðskiptin (Thank you for your business)

The words were from receipts.