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 $184.26   7.103%   $197.348   $197.35   $197.35   $197.30  
  Purchase #2 $89.49   7.198%   $95.9315   $95.93   $95.95   $95.90  
  Purchase #3 $128.66   4.483%   $134.4278   $134.43   $134.45   $134.40  
  Purchase #4 $149.31   5.578%   $157.6385   $157.64   $157.65   $157.60  
  Purchase #5 $245.96   5.254%   $258.8827   $258.88   $258.90   $258.90  
  Purchase #6 $150.93   10.781%   $167.2018   $167.20   $167.20   $167.20  
  Purchase #7 $114.87   4.419%   $119.9461   $119.95   $119.95   $119.90  
  7 purchase totals = $1,063.48       $1,131.3764   $1,131.38   $1,131.45   $1,131.20