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	$156.79	3.735%	$162.6461	$162.65	$162.65	$162.60
Purchase #2	$63.48	13.850%	$72.272	$72.27	$72.25	$72.30
Purchase #3	$172.88	3.562%	$179.038	$179.04	$179.05	$179.00
Purchase #4	$183.51	4.821%	$192.357	$192.36	$192.35	$192.40
Purchase #5	$162.63	5.839%	$172.126	$172.13	$172.15	$172.10
Purchase #6	$16.72	11.507%	$18.644	$18.64	$18.65	$18.60
Purchase #7	$8.55	10.558%	$9.4527	$9.45	$9.45	$9.50
7 purchase totals =	$764.56		$806.5358	$806.54	$806.55	$806.50