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	$195.45	4.192%	$203.6433	$203.64	$203.65	$203.60
Purchase #2	$196.58	9.598%	$215.4477	$215.45	$215.45	$215.40
Purchase #3	$43.77	3.625%	$45.3567	$45.36	$45.35	$45.40
Purchase #4	$53.29	5.838%	$56.4011	$56.40	$56.40	$56.40
Purchase #5	$172.90	3.248%	$178.5158	$178.52	$178.50	$178.50
Purchase #6	$89.96	10.542%	$99.4436	$99.44	$99.45	$99.40
Purchase #7	$205.48	12.562%	$231.2924	$231.29	$231.30	$231.30
7 purchase totals =	$957.43		$1,030.1006	$1,030.10	$1,030.10	$1,030.00