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	$158.46	8.643%	$172.1557	$172.16	$172.15	$172.20
Purchase #2	$183.89	4.649%	$192.439	$192.44	$192.45	$192.40
Purchase #3	$34.25	11.263%	$38.1076	$38.11	$38.10	$38.10
Purchase #4	$242.76	4.653%	$254.0556	$254.06	$254.05	$254.10
Purchase #5	$150.90	11.455%	$168.1856	$168.19	$168.20	$168.20
Purchase #6	$161.69	8.385%	$175.2477	$175.25	$175.25	$175.20
Purchase #7	$22.54	12.618%	$25.3841	$25.38	$25.40	$25.40
7 purchase totals =	$954.49		$1,025.5753	$1,025.59	$1,025.60	$1,025.60