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	$200.60	4.543%	$209.7133	$209.71	$209.70	$209.70
Purchase #2	$166.81	13.507%	$189.341	$189.34	$189.35	$189.30
Purchase #3	$165.57	4.309%	$172.7044	$172.70	$172.70	$172.70
Purchase #4	$104.37	13.406%	$118.3618	$118.36	$118.35	$118.40
Purchase #5	$50.37	11.355%	$56.0895	$56.09	$56.10	$56.10
Purchase #6	$144.31	10.134%	$158.9344	$158.93	$158.95	$158.90
Purchase #7	$146.54	10.619%	$162.1011	$162.10	$162.10	$162.10
7 purchase totals =	$978.57		$1,067.2455	$1,067.23	$1,067.25	$1,067.20