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	$90.25	6.188%	$95.8347	$95.83	$95.85	$95.80
Purchase #2	$11.60	13.619%	$13.1798	$13.18	$13.20	$13.20
Purchase #3	$198.63	10.541%	$219.5676	$219.57	$219.55	$219.60
Purchase #4	$91.33	7.440%	$98.125	$98.13	$98.15	$98.10
Purchase #5	$215.81	7.442%	$231.8706	$231.87	$231.85	$231.90
Purchase #6	$237.32	12.714%	$267.4929	$267.49	$267.50	$267.50
Purchase #7	$212.91	13.815%	$242.3235	$242.32	$242.30	$242.30
7 purchase totals =	$1,057.85		$1,168.3941	$1,168.39	$1,168.40	$1,168.40