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	$119.66	7.758%	$128.9432	$128.94	$128.95	$128.90
Purchase #2	$60.57	9.404%	$66.266	$66.27	$66.25	$66.30
Purchase #3	$56.31	10.404%	$62.1685	$62.17	$62.15	$62.20
Purchase #4	$143.26	5.505%	$151.1465	$151.15	$151.15	$151.10
Purchase #5	$223.52	7.780%	$240.9099	$240.91	$240.90	$240.90
Purchase #6	$237.97	3.463%	$246.2109	$246.21	$246.20	$246.20
Purchase #7	$113.28	9.132%	$123.6247	$123.62	$123.60	$123.60
7 purchase totals =	$954.57		$1,019.2697	$1,019.27	$1,019.20	$1,019.20