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	$97.83	7.870%	$105.5292	$105.53	$105.55	$105.50
Purchase #2	$143.57	11.530%	$160.1236	$160.12	$160.10	$160.10
Purchase #3	$99.47	10.826%	$110.2386	$110.24	$110.25	$110.20
Purchase #4	$156.48	9.709%	$171.6726	$171.67	$171.65	$171.70
Purchase #5	$139.45	6.495%	$148.5073	$148.51	$148.50	$148.50
Purchase #6	$144.79	4.573%	$151.4112	$151.41	$151.40	$151.40
Purchase #7	$201.43	6.202%	$213.9227	$213.92	$213.90	$213.90
7 purchase totals =	$983.02		$1,061.4052	$1,061.40	$1,061.35	$1,061.30