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 $41.29   11.359%   $45.9801   $45.98   $46.00   $46.00  
  Purchase #2 $211.74   3.748%   $219.676   $219.68   $219.70   $219.70  
  Purchase #3 $172.89   5.253%   $181.9719   $181.97   $181.95   $182.00  
  Purchase #4 $196.97   8.155%   $213.0329   $213.03   $213.05   $213.00  
  Purchase #5 $135.31   7.580%   $145.5665   $145.57   $145.55   $145.60  
  Purchase #6 $248.86   10.438%   $274.836   $274.84   $274.85   $274.80  
  Purchase #7 $79.93   3.423%   $82.666   $82.67   $82.65   $82.70  
  7 purchase totals = $1,086.99       $1,163.7294   $1,163.74   $1,163.75   $1,163.80