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	$91.44	10.435%	$100.9818	$100.98	$101.00	$101.00
Purchase #2	$151.33	11.684%	$169.0114	$169.01	$169.00	$169.00
Purchase #3	$201.34	11.163%	$223.8156	$223.82	$223.80	$223.80
Purchase #4	$126.92	12.588%	$142.8967	$142.90	$142.90	$142.90
Purchase #5	$6.26	4.561%	$6.5455	$6.55	$6.55	$6.50
Purchase #6	$187.31	8.826%	$203.842	$203.84	$203.85	$203.80
Purchase #7	$242.85	13.862%	$276.5139	$276.51	$276.50	$276.50
7 purchase totals =	$1,007.45		$1,123.6069	$1,123.61	$1,123.60	$1,123.50