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	$140.29	12.625%	$158.0016	$158.00	$158.00	$158.00
Purchase #2	$88.55	12.489%	$99.609	$99.61	$99.60	$99.60
Purchase #3	$167.92	5.679%	$177.4562	$177.46	$177.45	$177.50
Purchase #4	$184.41	5.327%	$194.2335	$194.23	$194.25	$194.20
Purchase #5	$90.57	10.371%	$99.963	$99.96	$99.95	$100.00
Purchase #6	$97.67	13.735%	$111.085	$111.09	$111.10	$111.10
Purchase #7	$199.67	6.649%	$212.9461	$212.95	$212.95	$212.90
7 purchase totals =	$969.08		$1,053.2944	$1,053.30	$1,053.30	$1,053.30