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	$175.59	8.536%	$190.5784	$190.58	$190.60	$190.60
Purchase #2	$165.47	4.469%	$172.8649	$172.86	$172.85	$172.90
Purchase #3	$109.32	3.689%	$113.3528	$113.35	$113.35	$113.40
Purchase #4	$155.61	10.608%	$172.1171	$172.12	$172.10	$172.10
Purchase #5	$24.89	3.486%	$25.7577	$25.76	$25.75	$25.80
Purchase #6	$222.97	13.354%	$252.7454	$252.75	$252.75	$252.70
Purchase #7	$76.56	13.630%	$86.9951	$87.00	$87.00	$87.00
7 purchase totals =	$930.41		$1,014.4114	$1,014.42	$1,014.40	$1,014.50