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	$66.92	3.800%	$69.463	$69.46	$69.45	$69.50
Purchase #2	$80.64	3.161%	$83.189	$83.19	$83.20	$83.20
Purchase #3	$152.39	8.488%	$165.3249	$165.32	$165.30	$165.30
Purchase #4	$186.95	11.706%	$208.8344	$208.83	$208.85	$208.80
Purchase #5	$60.72	3.167%	$62.643	$62.64	$62.65	$62.60
Purchase #6	$91.25	8.535%	$99.0382	$99.04	$99.05	$99.00
Purchase #7	$211.92	5.539%	$223.6582	$223.66	$223.65	$223.70
7 purchase totals =	$850.79		$912.1507	$912.14	$912.15	$912.10