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	$193.40	9.235%	$211.2605	$211.26	$211.25	$211.30
Purchase #2	$102.50	11.737%	$114.5304	$114.53	$114.55	$114.50
Purchase #3	$189.74	3.733%	$196.823	$196.82	$196.80	$196.80
Purchase #4	$121.92	12.784%	$137.5063	$137.51	$137.50	$137.50
Purchase #5	$149.86	4.736%	$156.9574	$156.96	$156.95	$157.00
Purchase #6	$103.80	5.243%	$109.2422	$109.24	$109.25	$109.20
Purchase #7	$187.60	6.686%	$200.1429	$200.14	$200.15	$200.10
7 purchase totals =	$1,048.82		$1,126.4627	$1,126.46	$1,126.45	$1,126.40