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 $209.48   7.525%   $225.2434   $225.24   $225.25   $225.20  
  Purchase #2 $41.35   7.679%   $44.5253   $44.53   $44.55   $44.50  
  Purchase #3 $177.84   13.319%   $201.5265   $201.53   $201.55   $201.50  
  Purchase #4 $61.30   3.653%   $63.5393   $63.54   $63.55   $63.50  
  Purchase #5 $219.70   9.383%   $240.3145   $240.31   $240.30   $240.30  
  Purchase #6 $212.46   3.676%   $220.27   $220.27   $220.25   $220.30  
  Purchase #7 $92.35   8.125%   $99.8534   $99.85   $99.85   $99.90  
  7 purchase totals = $1,014.48       $1,095.2724   $1,095.27   $1,095.30   $1,095.20