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 $182.76   6.717%   $195.036   $195.04   $195.05   $195.00  
  Purchase #2 $200.79   12.432%   $225.7522   $225.75   $225.75   $225.80  
  Purchase #3 $15.96   11.477%   $17.7917   $17.79   $17.80   $17.80  
  Purchase #4 $173.36   9.671%   $190.1256   $190.13   $190.15   $190.10  
  Purchase #5 $78.71   7.847%   $84.8864   $84.89   $84.90   $84.90  
  Purchase #6 $207.97   4.278%   $216.867   $216.87   $216.85   $216.90  
  Purchase #7 $246.59   12.191%   $276.6518   $276.65   $276.65   $276.70  
  7 purchase totals = $1,106.14       $1,207.1107   $1,207.12   $1,207.15   $1,207.20