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	$173.52	13.222%	$196.4628	$196.46	$196.45	$196.50
Purchase #2	$69.88	10.384%	$77.1363	$77.14	$77.15	$77.10
Purchase #3	$92.50	8.295%	$100.1729	$100.17	$100.15	$100.20
Purchase #4	$135.83	9.746%	$149.068	$149.07	$149.05	$149.10
Purchase #5	$33.56	6.499%	$35.7411	$35.74	$35.75	$35.70
Purchase #6	$163.49	13.559%	$185.6576	$185.66	$185.65	$185.70
Purchase #7	$159.37	8.615%	$173.0997	$173.10	$173.10	$173.10
7 purchase totals =	$828.15		$917.3384	$917.34	$917.30	$917.40