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 $182.54   8.297%   $197.6853   $197.69   $197.70   $197.70  
  Purchase #2 $187.93   3.333%   $194.1937   $194.19   $194.20   $194.20  
  Purchase #3 $36.65   13.707%   $41.6736   $41.67   $41.65   $41.70  
  Purchase #4 $238.59   10.829%   $264.4269   $264.43   $264.45   $264.40  
  Purchase #5 $162.67   8.699%   $176.8207   $176.82   $176.80   $176.80  
  Purchase #6 $85.95   5.848%   $90.9764   $90.98   $91.00   $91.00  
  Purchase #7 $184.65   5.242%   $194.3294   $194.33   $194.35   $194.30  
  7 purchase totals = $1,078.98       $1,160.1060   $1,160.11   $1,160.15   $1,160.10