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 $69.87   9.426%   $76.4559   $76.46   $76.45   $76.50  
  Purchase #2 $186.45   13.827%   $212.2304   $212.23   $212.25   $212.20  
  Purchase #3 $68.89   4.855%   $72.2346   $72.23   $72.25   $72.20  
  Purchase #4 $243.79   7.568%   $262.24   $262.24   $262.25   $262.20  
  Purchase #5 $146.55   13.311%   $166.0573   $166.06   $166.05   $166.10  
  Purchase #6 $211.35   6.361%   $224.794   $224.79   $224.80   $224.80  
  Purchase #7 $96.71   3.594%   $100.1858   $100.19   $100.20   $100.20  
  7 purchase totals = $1,023.61       $1,114.1980   $1,114.20   $1,114.25   $1,114.20