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	$121.67	3.334%	$125.7265	$125.73	$125.75	$125.70
Purchase #2	$75.91	10.533%	$83.9056	$83.91	$83.90	$83.90
Purchase #3	$247.37	7.456%	$265.8139	$265.81	$265.80	$265.80
Purchase #4	$41.94	4.643%	$43.8873	$43.89	$43.90	$43.90
Purchase #5	$164.36	13.498%	$186.5453	$186.55	$186.55	$186.50
Purchase #6	$77.93	5.747%	$82.4086	$82.41	$82.40	$82.40
Purchase #7	$202.56	5.800%	$214.3085	$214.31	$214.30	$214.30
7 purchase totals =	$931.74		$1,002.5957	$1,002.61	$1,002.60	$1,002.50