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	$203.96	9.210%	$222.7447	$222.74	$222.75	$222.70
Purchase #2	$230.89	8.824%	$251.2637	$251.26	$251.25	$251.30
Purchase #3	$82.77	10.600%	$91.5436	$91.54	$91.55	$91.50
Purchase #4	$134.38	11.675%	$150.0689	$150.07	$150.05	$150.10
Purchase #5	$73.34	4.209%	$76.4269	$76.43	$76.45	$76.40
Purchase #6	$171.54	5.780%	$181.455	$181.46	$181.45	$181.50
Purchase #7	$197.71	5.530%	$208.6434	$208.64	$208.65	$208.60
7 purchase totals =	$1,094.59		$1,182.1462	$1,182.14	$1,182.15	$1,182.10