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	$105.38	5.471%	$111.1453	$111.15	$111.15	$111.10
Purchase #2	$159.29	5.326%	$167.7738	$167.77	$167.75	$167.80
Purchase #3	$152.53	12.136%	$171.041	$171.04	$171.05	$171.00
Purchase #4	$40.61	12.225%	$45.5746	$45.57	$45.55	$45.60
Purchase #5	$120.72	8.510%	$130.9933	$130.99	$131.00	$131.00
Purchase #6	$163.53	9.367%	$178.8479	$178.85	$178.85	$178.80
Purchase #7	$207.46	4.664%	$217.1359	$217.14	$217.15	$217.10
7 purchase totals =	$949.52		$1,022.5118	$1,022.51	$1,022.50	$1,022.40