Jose Baxter scored two penalties with Che Adams also converting a spot-kick. Matt Done and Stefan Scougall were United's other scorers while Jon Stead netted County's consolation.
Baxter opened the scoring from the spot in the 20th minute after Jamal Campbell-Ryce was fouled by Thierry Audel.
Liam Noble went close to equalising when his lob beat goalkeeper George Long, only for the ball to come back off the bar.
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Done made it 2-0 in the 23rd minute when he found himself one-on-one with Loach and dinked the ball over the keeper.
Baxter scored his second penalty on 36 minutes after Haydn Hollis fouled Adams.
Substitute Stead pulled a goal back for Notts shortly after the hour, bundling the ball in from close range after meeting a low cross from Elliott Hewitt.
Scougall restored United's three-goal advantage in the 67th minute with a neat finish from inside the area.
On 74 minutes, Adams completed the scoring with another penalty after being hauled down by Hollis, who was sent off as a result.
Tuesday's JPT results
Bristol Rovers 2-0 Wycombe
Bury 0-1 Morecambe
Bradford P-P Barnsley
Crawley 0-3 Southend
Crewe 2-3 Wigan
Fleetwood 2-1 Shrewsbury
Gillingham 2-1 Luton
Millwall 2-0 Northampton
Oxford 2-0 Swindon
Plymouth 2-0 Exeter
Port Vale 1-2 Blackpool
Rochdale 2-1 Chesterfield
Sheffield United 5-1 Notts County
Yeovil 0-0 Coventry (pens: 4-3)
York 2-0 Doncaster
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