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 $86.34   10.266%   $95.2037   $95.20   $95.20   $95.20  
  Purchase #2 $198.58   13.692%   $225.7696   $225.77   $225.75   $225.80  
  Purchase #3 $174.62   4.384%   $182.2753   $182.28   $182.30   $182.30  
  Purchase #4 $122.36   8.525%   $132.7912   $132.79   $132.80   $132.80  
  Purchase #5 $216.93   11.579%   $242.0483   $242.05   $242.05   $242.00  
  Purchase #6 $23.39   6.261%   $24.8544   $24.85   $24.85   $24.90  
  Purchase #7 $204.84   4.368%   $213.7874   $213.79   $213.80   $213.80  
  7 purchase totals = $1,027.06       $1,116.7299   $1,116.73   $1,116.75   $1,116.80