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	$222.49	10.316%	$245.4421	$245.44	$245.45	$245.40
Purchase #2	$72.61	11.189%	$80.7343	$80.73	$80.75	$80.70
Purchase #3	$227.57	7.373%	$244.3487	$244.35	$244.35	$244.30
Purchase #4	$33.40	3.149%	$34.4518	$34.45	$34.45	$34.50
Purchase #5	$53.59	10.231%	$59.0728	$59.07	$59.05	$59.10
Purchase #6	$187.69	10.144%	$206.7293	$206.73	$206.75	$206.70
Purchase #7	$150.68	11.239%	$167.6149	$167.61	$167.60	$167.60
7 purchase totals =	$948.03		$1,038.3939	$1,038.38	$1,038.40	$1,038.30