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	$185.52	3.741%	$192.4603	$192.46	$192.45	$192.50
Purchase #2	$79.79	10.832%	$88.4329	$88.43	$88.45	$88.40
Purchase #3	$9.98	13.823%	$11.3595	$11.36	$11.35	$11.40
Purchase #4	$207.60	13.797%	$236.2426	$236.24	$236.25	$236.20
Purchase #5	$209.38	11.537%	$233.5362	$233.54	$233.55	$233.50
Purchase #6	$209.40	4.365%	$218.5403	$218.54	$218.55	$218.50
Purchase #7	$101.28	13.398%	$114.8495	$114.85	$114.85	$114.80
7 purchase totals =	$1,002.95		$1,095.4213	$1,095.42	$1,095.45	$1,095.30