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 $88.95   9.575%   $97.467   $97.47   $97.45   $97.50  
  Purchase #2 $190.61   7.596%   $205.0887   $205.09   $205.10   $205.10  
  Purchase #3 $59.29   3.771%   $61.5258   $61.53   $61.55   $61.50  
  Purchase #4 $234.95   9.717%   $257.7801   $257.78   $257.80   $257.80  
  Purchase #5 $242.75   8.367%   $263.0609   $263.06   $263.05   $263.10  
  Purchase #6 $102.96   4.648%   $107.7456   $107.75   $107.75   $107.70  
  Purchase #7 $158.55   10.146%   $174.6365   $174.64   $174.65   $174.60  
  7 purchase totals = $1,078.06       $1,167.3046   $1,167.32   $1,167.35   $1,167.30