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	$150.75	9.260%	$164.7095	$164.71	$164.70	$164.70
Purchase #2	$98.56	4.363%	$102.8602	$102.86	$102.85	$102.90
Purchase #3	$154.98	7.533%	$166.6546	$166.65	$166.65	$166.70
Purchase #4	$125.45	5.110%	$131.8605	$131.86	$131.85	$131.90
Purchase #5	$208.87	7.362%	$224.247	$224.25	$224.25	$224.20
Purchase #6	$55.82	12.535%	$62.817	$62.82	$62.80	$62.80
Purchase #7	$249.40	4.542%	$260.7277	$260.73	$260.75	$260.70
7 purchase totals =	$1,043.83		$1,113.8765	$1,113.88	$1,113.85	$1,113.90