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 $84.41   13.220%   $95.569   $95.57   $95.55   $95.60  
  Purchase #2 $160.93   8.697%   $174.9261   $174.93   $174.95   $174.90  
  Purchase #3 $157.62   7.752%   $169.8387   $169.84   $169.85   $169.80  
  Purchase #4 $195.33   10.492%   $215.824   $215.82   $215.80   $215.80  
  Purchase #5 $44.92   3.376%   $46.4365   $46.44   $46.45   $46.40  
  Purchase #6 $200.33   11.345%   $223.0574   $223.06   $223.05   $223.10  
  Purchase #7 $33.56   13.525%   $38.099   $38.10   $38.10   $38.10  
  7 purchase totals = $877.10       $963.7507   $963.76   $963.75   $963.70