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	$164.42	10.735%	$182.0705	$182.07	$182.05	$182.10
Purchase #2	$103.70	7.765%	$111.7523	$111.75	$111.75	$111.80
Purchase #3	$50.77	13.440%	$57.5935	$57.59	$57.60	$57.60
Purchase #4	$183.91	10.473%	$203.1709	$203.17	$203.15	$203.20
Purchase #5	$198.49	11.808%	$221.9277	$221.93	$221.95	$221.90
Purchase #6	$193.36	3.706%	$200.5259	$200.53	$200.55	$200.50
Purchase #7	$59.51	9.696%	$65.2801	$65.28	$65.30	$65.30
7 purchase totals =	$954.16		$1,042.3209	$1,042.32	$1,042.35	$1,042.40