As of the census of 2010, 539 people in 202 households and 155 families resided in the town.
The population density was 2,695 people per square mile (1040.5/km²).
There were 218 housing units at an average density of 1090 per square mile (420.9/km²).
Of that population, 93.32% was White; 2.78%, African American; 1.11%, Asian; and 0.93% of the population was mixed-race.
 Hispanics or Latinos of any race constituted 3.53% of the population.

There were 202 households, out of which 40.6% had children under the age of 18 living with them, 59.9% were married couples living together, 12.9% had a female householder with no husband present, 4.0% had a male householder with no wife present, and 23.3% were non-families.
19.8% of all households were made up of individuals, and 5.5% had someone living alone who was 65 years of age or older.
The average household size was 2.67 and the average family size was 3.06.

In the town, the population was spread out, with 30.7% under the age of 20, 5.5% from 20 to 29, 20.2% from 30 to 44, 34.0% from 45 to 64 (up from 23% in 2005), and 9.7% who were 65 years of age or older.
The median age was 40.5 years (up from 36 years in 2005).
For every 100 females, there were 94.6 males.
For every 100 females age 18 and over, there were 89.1 males.

The median estimated income for a household in the town in 2010 was $92,292, and the median estimated income for a family in 2010 was $93,750.
Males had a median income of $79,000 versus $55,208 for females.
The per capita income for the town was $39,380.
In 2005, about 4.2% of families and 5.4% of the population were below the poverty line, including 3.5% of those under age 18 and 15.7% of those age 65 or over.
Poverty level data was not provided for 2010.
As of the census of 2010, 539 people in 202 households and 155 families resided in the town. The population density was 2,695 people per square mile (1040.5/km²). There were 218 housing units at an average density of 1090 per square mile (420.9/km²). Of that population, 93.32% was White; 2.78%, African American; 1.11%, Asian; and 0.93% of the population was mixed-race.  Hispanics or Latinos of any race constituted 3.53% of the population.
There were 202 households, out of which 40.6% had children under the age of 18 living with them, 59.9% were married couples living together, 12.9% had a female householder with no husband present, 4.0% had a male householder with no wife present, and 23.3% were non-families. 19.8% of all households were made up of individuals, and 5.5% had someone living alone who was 65 years of age or older. The average household size was 2.67 and the average family size was 3.06.
In the town, the population was spread out, with 30.7% under the age of 20, 5.5% from 20 to 29, 20.2% from 30 to 44, 34.0% from 45 to 64 (up from 23% in 2005), and 9.7% who were 65 years of age or older. The median age was 40.5 years (up from 36 years in 2005). For every 100 females, there were 94.6 males. For every 100 females age 18 and over, there were 89.1 males.
The median estimated income for a household in the town in 2010 was $92,292, and the median estimated income for a family in 2010 was $93,750. Males had a median income of $79,000 versus $55,208 for females. The per capita income for the town was $39,380. In 2005, about 4.2% of families and 5.4% of the population were below the poverty line, including 3.5% of those under age 18 and 15.7% of those age 65 or over. Poverty level data was not provided for 2010.
Round Hill, Loudoun County, Virginia