Commonly used in casual conversation rather than formal settings. I'll be finishing work at five, there or thereabouts.
Pro Tip 2/3
Indicating Uncertainty
Used when you're not sure of the exact time or place but it's close to what you mention. The keys should be on the table, there or thereabouts.
Pro Tip 3/3
Flexible Estimates
Helpful when giving approximate figures or quantities, suggesting a little more or less is acceptable. We raised £1000 for charity, there or thereabouts.