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	$239.67	9.815%	$263.1936	$263.19	$263.20	$263.20
Purchase #2	$123.47	4.621%	$129.1755	$129.18	$129.20	$129.20
Purchase #3	$225.94	5.694%	$238.805	$238.81	$238.80	$238.80
Purchase #4	$32.52	11.408%	$36.2299	$36.23	$36.25	$36.20
Purchase #5	$95.67	10.683%	$105.8904	$105.89	$105.90	$105.90
Purchase #6	$187.99	6.594%	$200.3861	$200.39	$200.40	$200.40
Purchase #7	$162.47	6.258%	$172.6374	$172.64	$172.65	$172.60
7 purchase totals =	$1,067.73		$1,146.3179	$1,146.33	$1,146.40	$1,146.30