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 $85.35   13.693%   $97.037   $97.04   $97.05   $97.00  
  Purchase #2 $218.66   10.523%   $241.6696   $241.67   $241.65   $241.70  
  Purchase #3 $203.54   6.780%   $217.34   $217.34   $217.35   $217.30  
  Purchase #4 $49.30   3.874%   $51.2099   $51.21   $51.20   $51.20  
  Purchase #5 $217.95   4.192%   $227.0865   $227.09   $227.10   $227.10  
  Purchase #6 $184.54   10.281%   $203.5126   $203.51   $203.50   $203.50  
  Purchase #7 $91.67   3.263%   $94.6612   $94.66   $94.65   $94.70  
  7 purchase totals = $1,051.01       $1,132.5168   $1,132.52   $1,132.50   $1,132.50