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	$186.31	13.746%	$211.9202	$211.92	$211.90	$211.90
Purchase #2	$10.42	10.862%	$11.5518	$11.55	$11.55	$11.60
Purchase #3	$89.85	12.261%	$100.8665	$100.87	$100.85	$100.90
Purchase #4	$65.67	13.763%	$74.7082	$74.71	$74.70	$74.70
Purchase #5	$59.81	12.520%	$67.2982	$67.30	$67.30	$67.30
Purchase #6	$146.80	11.741%	$164.0358	$164.04	$164.05	$164.00
Purchase #7	$223.28	4.439%	$233.1914	$233.19	$233.20	$233.20
7 purchase totals =	$782.14		$863.5721	$863.58	$863.55	$863.60