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	$192.66	4.253%	$200.8538	$200.85	$200.85	$200.90
Purchase #2	$111.45	4.326%	$116.2713	$116.27	$116.25	$116.30
Purchase #3	$30.96	4.764%	$32.4349	$32.43	$32.45	$32.40
Purchase #4	$98.37	13.455%	$111.6057	$111.61	$111.60	$111.60
Purchase #5	$230.84	7.470%	$248.0837	$248.08	$248.10	$248.10
Purchase #6	$69.53	4.699%	$72.7972	$72.80	$72.80	$72.80
Purchase #7	$210.55	9.643%	$230.8533	$230.85	$230.85	$230.90
7 purchase totals =	$944.36		$1,012.8999	$1,012.89	$1,012.90	$1,013.00