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 $158.87   10.766%   $175.9739   $175.97   $175.95   $176.00  
  Purchase #2 $48.59   11.748%   $54.2984   $54.30   $54.30   $54.30  
  Purchase #3 $164.45   5.537%   $173.5556   $173.56   $173.55   $173.60  
  Purchase #4 $85.80   9.140%   $93.6421   $93.64   $93.65   $93.60  
  Purchase #5 $142.45   12.774%   $160.6466   $160.65   $160.65   $160.60  
  Purchase #6 $166.48   9.765%   $182.7368   $182.74   $182.75   $182.70  
  Purchase #7 $191.93   10.702%   $212.4703   $212.47   $212.45   $212.50  
  7 purchase totals = $958.57       $1,053.3237   $1,053.33   $1,053.30   $1,053.30