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	$153.93	4.571%	$160.9661	$160.97	$160.95	$161.00
Purchase #2	$44.36	4.601%	$46.401	$46.40	$46.40	$46.40
Purchase #3	$231.53	8.595%	$251.43	$251.43	$251.45	$251.40
Purchase #4	$141.58	4.153%	$147.4598	$147.46	$147.45	$147.50
Purchase #5	$55.80	12.561%	$62.809	$62.81	$62.80	$62.80
Purchase #6	$95.84	4.221%	$99.8854	$99.89	$99.90	$99.90
Purchase #7	$245.52	5.645%	$259.3796	$259.38	$259.40	$259.40
7 purchase totals =	$968.56		$1,028.3309	$1,028.34	$1,028.35	$1,028.40