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	$191.53	3.707%	$198.63	$198.63	$198.65	$198.60
Purchase #2	$167.85	12.156%	$188.2538	$188.25	$188.25	$188.30
Purchase #3	$145.30	10.834%	$161.0418	$161.04	$161.05	$161.00
Purchase #4	$148.41	7.727%	$159.8776	$159.88	$159.90	$159.90
Purchase #5	$54.76	8.192%	$59.2459	$59.25	$59.25	$59.20
Purchase #6	$145.76	5.642%	$153.9838	$153.98	$154.00	$154.00
Purchase #7	$166.43	7.491%	$178.8973	$178.90	$178.90	$178.90
7 purchase totals =	$1,020.04		$1,099.9302	$1,099.93	$1,100.00	$1,099.90