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	$111.46	4.863%	$116.8803	$116.88	$116.90	$116.90
Purchase #2	$11.48	3.771%	$11.9129	$11.91	$11.90	$11.90
Purchase #3	$60.50	7.202%	$64.8572	$64.86	$64.85	$64.90
Purchase #4	$236.39	8.118%	$255.5801	$255.58	$255.60	$255.60
Purchase #5	$192.98	13.583%	$219.1925	$219.19	$219.20	$219.20
Purchase #6	$171.33	6.362%	$182.23	$182.23	$182.25	$182.20
Purchase #7	$40.26	8.520%	$43.6902	$43.69	$43.70	$43.70
7 purchase totals =	$824.40		$894.3432	$894.34	$894.40	$894.40