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	$64.74	10.823%	$71.7468	$71.75	$71.75	$71.70
Purchase #2	$192.83	5.681%	$203.7847	$203.78	$203.80	$203.80
Purchase #3	$112.47	4.657%	$117.7077	$117.71	$117.70	$117.70
Purchase #4	$29.87	9.427%	$32.6858	$32.69	$32.70	$32.70
Purchase #5	$178.29	10.196%	$196.4684	$196.47	$196.45	$196.50
Purchase #6	$148.86	6.259%	$158.1771	$158.18	$158.20	$158.20
Purchase #7	$226.85	6.498%	$241.5907	$241.59	$241.60	$241.60
7 purchase totals =	$953.91		$1,022.1612	$1,022.17	$1,022.20	$1,022.20