From a Jain Dharma perspective, there isn’t a canonical practice of using talismans or external protections specifically against the “evil eye.” Jainism emphasizes inner purity, ethical conduct, and reverence for tirthankaras rather than relying on superstitious objects for protection.

What you can do that aligns with Jain practice:

• Keep the shop and surroundings clean and orderly, which reflects discipline and care.
• Place a simple, respectful Jain symbol or image (for example, a Swastik or a small Jain idol) in a clean, prominent, altar-like spot. Such symbols are revered in Jainism as auspicious and to remind us of right conduct, not as magic.
• If you want decorative, choose symbols tied to Jain teaching and reverence (like the Swastik or a Panch Parmatma emblem) and ensure anything installed is treated with respect and not treated as a magical charm.
• Focus on ethical business practices: truthful dealings, fair pricing, and generosity (daan) to those in need. Such acts are believed to bring true and lasting auspiciousness.

Important note: If someone or a community emphasizes magical protections or spells, gently steer toward Jain teachings on restraint from superstition and emphasis on inner virtue.

If you’d like, I can point you to Jain-specific symbols and their meanings using authentic Jain sources.