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 $60.32   4.352%   $62.9451   $62.95   $62.95   $62.90  
  Purchase #2 $33.73   8.356%   $36.5485   $36.55   $36.55   $36.50  
  Purchase #3 $153.53   11.167%   $170.6747   $170.67   $170.65   $170.70  
  Purchase #4 $118.67   6.313%   $126.1616   $126.16   $126.15   $126.20  
  Purchase #5 $97.49   9.135%   $106.3957   $106.40   $106.40   $106.40  
  Purchase #6 $193.80   6.156%   $205.7303   $205.73   $205.75   $205.70  
  Purchase #7 $155.96   7.118%   $167.0612   $167.06   $167.05   $167.10  
  7 purchase totals = $813.50       $875.5171   $875.52   $875.50   $875.50