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	$156.62	5.165%	$164.7094	$164.71	$164.70	$164.70
Purchase #2	$140.74	7.320%	$151.0422	$151.04	$151.05	$151.00
Purchase #3	$66.54	8.810%	$72.4022	$72.40	$72.40	$72.40
Purchase #4	$9.43	8.700%	$10.2504	$10.25	$10.25	$10.30
Purchase #5	$190.64	5.358%	$200.8545	$200.85	$200.85	$200.90
Purchase #6	$248.79	7.427%	$267.2676	$267.27	$267.25	$267.30
Purchase #7	$207.98	3.660%	$215.5921	$215.59	$215.60	$215.60
7 purchase totals =	$1,020.74		$1,082.1184	$1,082.11	$1,082.10	$1,082.20