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	$220.51	11.104%	$244.9954	$245.00	$245.00	$245.00
Purchase #2	$83.47	4.230%	$87.0008	$87.00	$87.00	$87.00
Purchase #3	$151.81	4.642%	$158.857	$158.86	$158.85	$158.90
Purchase #4	$103.47	9.485%	$113.2841	$113.28	$113.30	$113.30
Purchase #5	$212.96	12.867%	$240.3616	$240.36	$240.35	$240.40
Purchase #6	$81.43	9.861%	$89.4598	$89.46	$89.45	$89.50
Purchase #7	$75.51	6.534%	$80.4438	$80.44	$80.45	$80.40
7 purchase totals =	$929.16		$1,014.4025	$1,014.40	$1,014.40	$1,014.50