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	$198.63	5.436%	$209.4275	$209.43	$209.45	$209.40
Purchase #2	$9.94	5.107%	$10.4476	$10.45	$10.45	$10.40
Purchase #3	$227.31	3.780%	$235.9023	$235.90	$235.90	$235.90
Purchase #4	$243.50	4.788%	$255.1588	$255.16	$255.15	$255.20
Purchase #5	$32.98	7.450%	$35.437	$35.44	$35.45	$35.40
Purchase #6	$107.87	6.463%	$114.8416	$114.84	$114.85	$114.80
Purchase #7	$40.32	13.724%	$45.8535	$45.85	$45.85	$45.90
7 purchase totals =	$860.55		$907.0683	$907.07	$907.10	$907.00