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	$108.33	3.251%	$111.8518	$111.85	$111.85	$111.90
Purchase #2	$10.31	12.532%	$11.602	$11.60	$11.60	$11.60
Purchase #3	$5.51	3.664%	$5.7119	$5.71	$5.70	$5.70
Purchase #4	$116.83	3.483%	$120.8992	$120.90	$120.90	$120.90
Purchase #5	$217.98	3.477%	$225.5592	$225.56	$225.55	$225.60
Purchase #6	$190.64	4.198%	$198.6431	$198.64	$198.65	$198.60
Purchase #7	$57.99	13.571%	$65.8598	$65.86	$65.85	$65.90
7 purchase totals =	$707.59		$740.1270	$740.12	$740.10	$740.20