Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $55.82   12.766%   $62.946   $62.95   $62.95   $62.90  
  Purchase #2 $210.92   11.693%   $235.5829   $235.58   $235.60   $235.60  
  Purchase #3 $194.41   13.200%   $220.0721   $220.07   $220.05   $220.10  
  Purchase #4 $235.26   7.502%   $252.9092   $252.91   $252.90   $252.90  
  Purchase #5 $18.39   10.529%   $20.3263   $20.33   $20.35   $20.30  
  Purchase #6 $164.43   3.698%   $170.5106   $170.51   $170.50   $170.50  
  Purchase #7 $94.93   6.104%   $100.7245   $100.72   $100.70   $100.70  
  7 purchase totals = $974.16       $1,063.0716   $1,063.07   $1,063.05   $1,063.00