Buying 10 items would definitely make this way more likely, because we have a base-10 counting system.
To simplify the problem, if you look at the cents digit, $0.09×10 items = $0.90. If you look at both cents digits, they were mostly $0.99. $0.99×10 items = $9.90.
All you’d need in either case there is something to cost $0.10 more to get a nice even number.
Buying 10 items would definitely make this way more likely, because we have a base-10 counting system.
To simplify the problem, if you look at the cents digit, $0.09×10 items = $0.90. If you look at both cents digits, they were mostly $0.99. $0.99×10 items = $9.90.
All you’d need in either case there is something to cost $0.10 more to get a nice even number.