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	$207.58	10.768%	$229.9322	$229.93	$229.95	$229.90
Purchase #2	$160.83	9.120%	$175.4977	$175.50	$175.50	$175.50
Purchase #3	$239.86	12.694%	$270.3078	$270.31	$270.30	$270.30
Purchase #4	$80.76	5.683%	$85.3496	$85.35	$85.35	$85.30
Purchase #5	$23.70	4.237%	$24.7042	$24.70	$24.70	$24.70
Purchase #6	$162.37	10.752%	$179.828	$179.83	$179.85	$179.80
Purchase #7	$98.28	13.656%	$111.7011	$111.70	$111.70	$111.70
7 purchase totals =	$973.38		$1,077.3206	$1,077.32	$1,077.35	$1,077.20