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	$197.88	3.726%	$205.253	$205.25	$205.25	$205.30
Purchase #2	$72.53	13.152%	$82.0691	$82.07	$82.05	$82.10
Purchase #3	$140.87	6.585%	$150.1463	$150.15	$150.15	$150.10
Purchase #4	$9.98	9.659%	$10.944	$10.94	$10.95	$10.90
Purchase #5	$176.62	13.456%	$200.386	$200.39	$200.40	$200.40
Purchase #6	$80.80	13.637%	$91.8187	$91.82	$91.80	$91.80
Purchase #7	$53.38	9.768%	$58.5942	$58.59	$58.60	$58.60
7 purchase totals =	$732.06		$799.2113	$799.21	$799.20	$799.20