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	$179.40	9.764%	$196.9166	$196.92	$196.90	$196.90
Purchase #2	$59.37	10.751%	$65.7529	$65.75	$65.75	$65.80
Purchase #3	$55.35	5.522%	$58.4064	$58.41	$58.40	$58.40
Purchase #4	$232.90	12.563%	$262.1592	$262.16	$262.15	$262.20
Purchase #5	$179.98	11.467%	$200.6183	$200.62	$200.60	$200.60
Purchase #6	$67.85	7.775%	$73.1253	$73.13	$73.15	$73.10
Purchase #7	$226.87	12.849%	$256.0205	$256.02	$256.00	$256.00
7 purchase totals =	$1,001.72		$1,112.9992	$1,113.01	$1,112.95	$1,113.00