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	$132.80	6.273%	$141.1305	$141.13	$141.15	$141.10
Purchase #2	$151.29	8.747%	$164.5233	$164.52	$164.50	$164.50
Purchase #3	$193.69	6.640%	$206.551	$206.55	$206.55	$206.60
Purchase #4	$99.56	3.220%	$102.7658	$102.77	$102.75	$102.80
Purchase #5	$111.57	6.287%	$118.5844	$118.58	$118.60	$118.60
Purchase #6	$161.76	8.715%	$175.8574	$175.86	$175.85	$175.90
Purchase #7	$123.30	6.752%	$131.6252	$131.63	$131.65	$131.60
7 purchase totals =	$973.97		$1,041.0376	$1,041.04	$1,041.05	$1,041.10