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	$149.35	10.463%	$164.9765	$164.98	$165.00	$165.00
Purchase #2	$53.35	12.332%	$59.9291	$59.93	$59.95	$59.90
Purchase #3	$160.81	8.789%	$174.9436	$174.94	$174.95	$174.90
Purchase #4	$88.57	5.357%	$93.3147	$93.31	$93.30	$93.30
Purchase #5	$162.28	3.663%	$168.2243	$168.22	$168.20	$168.20
Purchase #6	$196.42	5.807%	$207.8261	$207.83	$207.85	$207.80
Purchase #7	$138.38	5.388%	$145.8359	$145.84	$145.85	$145.80
7 purchase totals =	$949.16		$1,015.0502	$1,015.05	$1,015.10	$1,014.90