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	$176.77	4.166%	$184.1342	$184.13	$184.15	$184.10
Purchase #2	$157.56	11.456%	$175.6101	$175.61	$175.60	$175.60
Purchase #3	$164.58	8.510%	$178.5858	$178.59	$178.60	$178.60
Purchase #4	$245.53	3.559%	$254.2684	$254.27	$254.25	$254.30
Purchase #5	$147.60	3.290%	$152.456	$152.46	$152.45	$152.50
Purchase #6	$37.90	11.338%	$42.1971	$42.20	$42.20	$42.20
Purchase #7	$213.73	3.406%	$221.0096	$221.01	$221.00	$221.00
7 purchase totals =	$1,143.67		$1,208.2612	$1,208.27	$1,208.25	$1,208.30