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	$38.67	7.269%	$41.4809	$41.48	$41.50	$41.50
Purchase #2	$46.76	11.331%	$52.0584	$52.06	$52.05	$52.10
Purchase #3	$245.56	9.689%	$269.3523	$269.35	$269.35	$269.40
Purchase #4	$187.27	7.298%	$200.937	$200.94	$200.95	$200.90
Purchase #5	$178.92	13.671%	$203.3802	$203.38	$203.40	$203.40
Purchase #6	$221.31	9.403%	$242.1198	$242.12	$242.10	$242.10
Purchase #7	$95.45	10.218%	$105.2031	$105.20	$105.20	$105.20
7 purchase totals =	$1,013.94		$1,114.5317	$1,114.53	$1,114.55	$1,114.60