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	$82.42	4.670%	$86.269	$86.27	$86.25	$86.30
Purchase #2	$192.81	5.828%	$204.047	$204.05	$204.05	$204.00
Purchase #3	$137.56	11.666%	$153.6077	$153.61	$153.60	$153.60
Purchase #4	$144.82	7.388%	$155.5193	$155.52	$155.50	$155.50
Purchase #5	$107.86	6.115%	$114.4556	$114.46	$114.45	$114.50
Purchase #6	$144.74	9.860%	$159.0114	$159.01	$159.00	$159.00
Purchase #7	$129.30	6.601%	$137.8351	$137.84	$137.85	$137.80
7 purchase totals =	$939.51		$1,010.7451	$1,010.76	$1,010.70	$1,010.70