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	$86.98	3.225%	$89.7851	$89.79	$89.80	$89.80
Purchase #2	$197.64	5.397%	$208.3066	$208.31	$208.30	$208.30
Purchase #3	$10.69	8.786%	$11.6292	$11.63	$11.65	$11.60
Purchase #4	$146.75	10.561%	$162.2483	$162.25	$162.25	$162.20
Purchase #5	$152.32	3.322%	$157.3801	$157.38	$157.40	$157.40
Purchase #6	$229.90	9.442%	$251.6072	$251.61	$251.60	$251.60
Purchase #7	$163.34	10.583%	$180.6263	$180.63	$180.65	$180.60
7 purchase totals =	$987.62		$1,061.5828	$1,061.60	$1,061.65	$1,061.50