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	$183.76	6.861%	$196.3678	$196.37	$196.35	$196.40
Purchase #2	$89.73	10.455%	$99.1113	$99.11	$99.10	$99.10
Purchase #3	$205.58	4.342%	$214.5063	$214.51	$214.50	$214.50
Purchase #4	$20.74	11.191%	$23.061	$23.06	$23.05	$23.10
Purchase #5	$225.97	3.278%	$233.3773	$233.38	$233.40	$233.40
Purchase #6	$149.28	13.329%	$169.1775	$169.18	$169.20	$169.20
Purchase #7	$185.84	6.819%	$198.5124	$198.51	$198.50	$198.50
7 purchase totals =	$1,060.90		$1,134.1136	$1,134.12	$1,134.10	$1,134.20