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 $187.68   4.456%   $196.043   $196.04   $196.05   $196.00  
  Purchase #2 $62.97   4.372%   $65.723   $65.72   $65.70   $65.70  
  Purchase #3 $156.25   11.137%   $173.6516   $173.65   $173.65   $173.70  
  Purchase #4 $167.74   8.287%   $181.6406   $181.64   $181.65   $181.60  
  Purchase #5 $12.95   4.561%   $13.5406   $13.54   $13.55   $13.50  
  Purchase #6 $131.95   13.128%   $149.2724   $149.27   $149.25   $149.30  
  Purchase #7 $231.82   6.369%   $246.5846   $246.58   $246.60   $246.60  
  7 purchase totals = $951.36       $1,026.4558   $1,026.44   $1,026.45   $1,026.40