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	$223.94	9.452%	$245.1068	$245.11	$245.10	$245.10
Purchase #2	$12.42	3.796%	$12.8915	$12.89	$12.90	$12.90
Purchase #3	$112.39	5.294%	$118.3399	$118.34	$118.35	$118.30
Purchase #4	$113.32	13.234%	$128.3168	$128.32	$128.30	$128.30
Purchase #5	$143.38	8.793%	$155.9874	$155.99	$156.00	$156.00
Purchase #6	$157.44	9.174%	$171.8835	$171.88	$171.90	$171.90
Purchase #7	$103.83	13.255%	$117.5927	$117.59	$117.60	$117.60
7 purchase totals =	$866.72		$950.1186	$950.12	$950.15	$950.10