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	$119.36	6.474%	$127.0874	$127.09	$127.10	$127.10
Purchase #2	$200.34	11.562%	$223.5033	$223.50	$223.50	$223.50
Purchase #3	$17.97	9.625%	$19.6996	$19.70	$19.70	$19.70
Purchase #4	$196.57	13.522%	$223.1502	$223.15	$223.15	$223.20
Purchase #5	$214.82	5.462%	$226.5535	$226.55	$226.55	$226.60
Purchase #6	$178.51	12.326%	$200.5131	$200.51	$200.50	$200.50
Purchase #7	$236.31	6.180%	$250.914	$250.91	$250.90	$250.90
7 purchase totals =	$1,163.88		$1,271.4211	$1,271.41	$1,271.40	$1,271.50