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	$102.50	9.215%	$111.9454	$111.95	$111.95	$111.90
Purchase #2	$203.49	4.283%	$212.2055	$212.21	$212.20	$212.20
Purchase #3	$36.34	4.434%	$37.9513	$37.95	$37.95	$38.00
Purchase #4	$87.39	5.855%	$92.5067	$92.51	$92.50	$92.50
Purchase #5	$71.33	8.466%	$77.3688	$77.37	$77.35	$77.40
Purchase #6	$68.90	13.471%	$78.1815	$78.18	$78.20	$78.20
Purchase #7	$134.73	8.152%	$145.7132	$145.71	$145.70	$145.70
7 purchase totals =	$704.68		$755.8724	$755.88	$755.85	$755.90