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	$243.96	7.701%	$262.7474	$262.75	$262.75	$262.70
Purchase #2	$137.58	3.292%	$142.1091	$142.11	$142.10	$142.10
Purchase #3	$146.44	6.411%	$155.8283	$155.83	$155.85	$155.80
Purchase #4	$123.72	5.709%	$130.7832	$130.78	$130.80	$130.80
Purchase #5	$103.31	10.775%	$114.4417	$114.44	$114.45	$114.40
Purchase #6	$89.77	13.167%	$101.59	$101.59	$101.60	$101.60
Purchase #7	$87.46	13.145%	$98.9566	$98.96	$98.95	$99.00
7 purchase totals =	$932.24		$1,006.4563	$1,006.46	$1,006.50	$1,006.40