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	$118.76	4.113%	$123.6446	$123.64	$123.65	$123.60
Purchase #2	$176.68	3.576%	$182.9981	$183.00	$183.00	$183.00
Purchase #3	$158.92	3.383%	$164.2963	$164.30	$164.30	$164.30
Purchase #4	$230.83	8.308%	$250.0074	$250.01	$250.00	$250.00
Purchase #5	$87.51	13.528%	$99.3484	$99.35	$99.35	$99.30
Purchase #6	$152.64	8.798%	$166.0693	$166.07	$166.05	$166.10
Purchase #7	$32.60	11.809%	$36.4497	$36.45	$36.45	$36.40
7 purchase totals =	$957.94		$1,022.8138	$1,022.82	$1,022.80	$1,022.70