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 $55.81   12.200%   $62.6188   $62.62   $62.60   $62.60  
  Purchase #2 $166.28   3.211%   $171.6193   $171.62   $171.60   $171.60  
  Purchase #3 $40.88   13.247%   $46.2954   $46.30   $46.30   $46.30  
  Purchase #4 $126.48   5.123%   $132.9596   $132.96   $132.95   $133.00  
  Purchase #5 $201.50   12.368%   $226.4215   $226.42   $226.40   $226.40  
  Purchase #6 $211.67   3.816%   $219.7473   $219.75   $219.75   $219.70  
  Purchase #7 $179.65   11.833%   $200.908   $200.91   $200.90   $200.90  
  7 purchase totals = $982.27       $1,060.5699   $1,060.58   $1,060.50   $1,060.50