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 $84.39   12.569%   $94.997   $95.00   $95.00   $95.00  
  Purchase #2 $131.39   10.263%   $144.8746   $144.87   $144.85   $144.90  
  Purchase #3 $142.84   10.595%   $157.9739   $157.97   $157.95   $158.00  
  Purchase #4 $231.72   9.870%   $254.5908   $254.59   $254.60   $254.60  
  Purchase #5 $245.58   8.561%   $266.6041   $266.60   $266.60   $266.60  
  Purchase #6 $46.72   4.427%   $48.7883   $48.79   $48.80   $48.80  
  Purchase #7 $215.52   11.501%   $240.307   $240.31   $240.30   $240.30  
  7 purchase totals = $1,098.16       $1,208.1357   $1,208.13   $1,208.10   $1,208.20