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	$132.49	11.836%	$148.1715	$148.17	$148.15	$148.20
Purchase #2	$39.51	10.691%	$43.734	$43.73	$43.75	$43.70
Purchase #3	$74.56	5.201%	$78.4379	$78.44	$78.45	$78.40
Purchase #4	$220.55	10.561%	$243.8423	$243.84	$243.85	$243.80
Purchase #5	$241.73	4.429%	$252.4362	$252.44	$252.45	$252.40
Purchase #6	$197.69	5.373%	$208.3119	$208.31	$208.30	$208.30
Purchase #7	$123.29	11.819%	$137.8616	$137.86	$137.85	$137.90
7 purchase totals =	$1,029.82		$1,112.7954	$1,112.79	$1,112.80	$1,112.70