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	$143.83	10.427%	$158.8272	$158.83	$158.85	$158.80
Purchase #2	$6.52	11.797%	$7.2892	$7.29	$7.30	$7.30
Purchase #3	$202.73	4.497%	$211.8468	$211.85	$211.85	$211.80
Purchase #4	$241.74	3.429%	$250.0293	$250.03	$250.05	$250.00
Purchase #5	$184.30	6.452%	$196.191	$196.19	$196.20	$196.20
Purchase #6	$146.81	8.183%	$158.8235	$158.82	$158.80	$158.80
Purchase #7	$106.31	11.450%	$118.4825	$118.48	$118.50	$118.50
7 purchase totals =	$1,032.24		$1,101.4895	$1,101.49	$1,101.55	$1,101.40