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 $85.58   7.645%   $92.1226   $92.12   $92.10   $92.10  
  Purchase #2 $116.98   7.417%   $125.6564   $125.66   $125.65   $125.70  
  Purchase #3 $156.82   10.500%   $173.2861   $173.29   $173.30   $173.30  
  Purchase #4 $64.59   6.406%   $68.7276   $68.73   $68.75   $68.70  
  Purchase #5 $248.40   7.537%   $267.1219   $267.12   $267.10   $267.10  
  Purchase #6 $197.33   11.118%   $219.2691   $219.27   $219.25   $219.30  
  Purchase #7 $195.83   7.165%   $209.8612   $209.86   $209.85   $209.90  
  7 purchase totals = $1,065.53       $1,156.0449   $1,156.05   $1,156.00   $1,156.10