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 $195.25   5.136%   $205.278   $205.28   $205.30   $205.30  
  Purchase #2 $63.56   5.683%   $67.1721   $67.17   $67.15   $67.20  
  Purchase #3 $219.99   11.352%   $244.9633   $244.96   $244.95   $245.00  
  Purchase #4 $43.42   13.734%   $49.3833   $49.38   $49.40   $49.40  
  Purchase #5 $121.76   6.645%   $129.851   $129.85   $129.85   $129.90  
  Purchase #6 $233.87   13.775%   $266.0856   $266.09   $266.10   $266.10  
  Purchase #7 $195.86   11.855%   $219.0792   $219.08   $219.10   $219.10  
  7 purchase totals = $1,073.71       $1,181.8125   $1,181.81   $1,181.85   $1,182.00