In Charts, Axis values are set dynamically basis the records shown in Chart. However, when the values shown on axis is a currency, it might have larger values, and these values are trimmed when shown on chart's axis.

Example: Top Customers Chart on Opportunity, gives Top 10 Accounts basis the Revenue. Here, if Revenue values are - 1000000000, 2000000000, and so on.. this value is trimmed and is shown as 10000... 20000... 30000... and so on, which does not clearly indicate the correct value unless user hovers over it.

Possible Solution can be to increase the intervals on X-axis to 4 times, so that complete value can be shown - example: 1000000000, 4000000000. So as to ensure complete value is shown.

Possibility to indicate interval when creating a chart can be an option or having dynamics intervals set automatically but in more robust way so that complete values are shown.