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	$208.43	11.816%	$233.0581	$233.06	$233.05	$233.10
Purchase #2	$73.53	12.567%	$82.7705	$82.77	$82.75	$82.80
Purchase #3	$44.27	5.753%	$46.8169	$46.82	$46.80	$46.80
Purchase #4	$238.30	10.824%	$264.0936	$264.09	$264.10	$264.10
Purchase #5	$59.77	8.444%	$64.817	$64.82	$64.80	$64.80
Purchase #6	$155.77	3.292%	$160.8979	$160.90	$160.90	$160.90
Purchase #7	$156.75	3.565%	$162.3381	$162.34	$162.35	$162.30
7 purchase totals =	$936.82		$1,014.7921	$1,014.80	$1,014.75	$1,014.80