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	$170.49	12.602%	$191.9751	$191.98	$192.00	$192.00
Purchase #2	$62.32	8.180%	$67.4178	$67.42	$67.40	$67.40
Purchase #3	$168.25	4.822%	$176.363	$176.36	$176.35	$176.40
Purchase #4	$61.37	9.788%	$67.3769	$67.38	$67.40	$67.40
Purchase #5	$144.78	5.423%	$152.6314	$152.63	$152.65	$152.60
Purchase #6	$211.38	3.822%	$219.4589	$219.46	$219.45	$219.50
Purchase #7	$119.32	13.678%	$135.6406	$135.64	$135.65	$135.60
7 purchase totals =	$937.91		$1,010.8637	$1,010.87	$1,010.90	$1,010.90