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 $211.57   7.649%   $227.753   $227.75   $227.75   $227.80  
  Purchase #2 $47.49   11.794%   $53.091   $53.09   $53.10   $53.10  
  Purchase #3 $225.34   4.278%   $234.98   $234.98   $235.00   $235.00  
  Purchase #4 $131.90   6.759%   $140.8151   $140.82   $140.80   $140.80  
  Purchase #5 $205.66   6.824%   $219.6942   $219.69   $219.70   $219.70  
  Purchase #6 $96.30   6.111%   $102.1849   $102.18   $102.20   $102.20  
  Purchase #7 $127.64   4.204%   $133.006   $133.01   $133.00   $133.00  
  7 purchase totals = $1,045.90       $1,111.5242   $1,111.52   $1,111.55   $1,111.60