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	$162.26	7.341%	$174.1715	$174.17	$174.15	$174.20
Purchase #2	$163.47	3.518%	$169.2209	$169.22	$169.20	$169.20
Purchase #3	$95.56	8.425%	$103.6109	$103.61	$103.60	$103.60
Purchase #4	$59.62	12.649%	$67.1613	$67.16	$67.15	$67.20
Purchase #5	$229.95	10.857%	$254.9157	$254.92	$254.90	$254.90
Purchase #6	$118.52	6.221%	$125.8931	$125.89	$125.90	$125.90
Purchase #7	$242.25	5.853%	$256.4289	$256.43	$256.45	$256.40
7 purchase totals =	$1,071.63		$1,151.4023	$1,151.40	$1,151.35	$1,151.40