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	$150.72	3.200%	$155.543	$155.54	$155.55	$155.50
Purchase #2	$52.63	11.780%	$58.8298	$58.83	$58.85	$58.80
Purchase #3	$163.61	3.653%	$169.5867	$169.59	$169.60	$169.60
Purchase #4	$201.73	12.305%	$226.5529	$226.55	$226.55	$226.60
Purchase #5	$205.74	10.833%	$228.0278	$228.03	$228.05	$228.00
Purchase #6	$86.51	4.137%	$90.0889	$90.09	$90.10	$90.10
Purchase #7	$161.89	6.795%	$172.8904	$172.89	$172.90	$172.90
7 purchase totals =	$1,022.83		$1,101.5195	$1,101.52	$1,101.60	$1,101.50