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	$176.47	3.613%	$182.8459	$182.85	$182.85	$182.80
Purchase #2	$141.33	3.309%	$146.0066	$146.01	$146.00	$146.00
Purchase #3	$131.79	10.408%	$145.5067	$145.51	$145.50	$145.50
Purchase #4	$211.44	4.519%	$220.995	$221.00	$221.00	$221.00
Purchase #5	$237.39	10.551%	$262.437	$262.44	$262.45	$262.40
Purchase #6	$62.85	5.526%	$66.3231	$66.32	$66.30	$66.30
Purchase #7	$82.52	3.384%	$85.3125	$85.31	$85.30	$85.30
7 purchase totals =	$1,043.79		$1,109.4268	$1,109.44	$1,109.40	$1,109.30