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 $58.91   5.354%   $62.064   $62.06   $62.05   $62.10  
  Purchase #2 $98.40   5.500%   $103.812   $103.81   $103.80   $103.80  
  Purchase #3 $39.80   8.479%   $43.1746   $43.17   $43.15   $43.20  
  Purchase #4 $46.37   11.764%   $51.825   $51.83   $51.85   $51.80  
  Purchase #5 $104.57   11.759%   $116.8664   $116.87   $116.85   $116.90  
  Purchase #6 $233.96   4.317%   $244.0601   $244.06   $244.05   $244.10  
  Purchase #7 $203.44   3.413%   $210.3834   $210.38   $210.40   $210.40  
  7 purchase totals = $785.45       $832.1855   $832.18   $832.15   $832.30