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 $201.82   4.670%   $211.245   $211.25   $211.25   $211.20  
  Purchase #2 $182.25   12.617%   $205.2445   $205.24   $205.25   $205.20  
  Purchase #3 $224.84   4.872%   $235.7942   $235.79   $235.80   $235.80  
  Purchase #4 $208.80   10.103%   $229.8951   $229.90   $229.90   $229.90  
  Purchase #5 $199.78   13.188%   $226.127   $226.13   $226.15   $226.10  
  Purchase #6 $124.52   4.873%   $130.5879   $130.59   $130.60   $130.60  
  Purchase #7 $204.78   9.853%   $224.957   $224.96   $224.95   $225.00  
  7 purchase totals = $1,346.79       $1,463.8507   $1,463.86   $1,463.90   $1,463.80