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	$181.46	11.294%	$201.9541	$201.95	$201.95	$202.00
Purchase #2	$106.82	4.319%	$111.4336	$111.43	$111.45	$111.40
Purchase #3	$5.55	11.250%	$6.1744	$6.17	$6.15	$6.20
Purchase #4	$166.92	3.354%	$172.5185	$172.52	$172.50	$172.50
Purchase #5	$47.78	12.494%	$53.7496	$53.75	$53.75	$53.70
Purchase #6	$150.89	11.600%	$168.3932	$168.39	$168.40	$168.40
Purchase #7	$166.89	5.505%	$176.0773	$176.08	$176.10	$176.10
7 purchase totals =	$826.31		$890.3007	$890.29	$890.30	$890.30