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	$219.76	9.653%	$240.9734	$240.97	$240.95	$241.00
Purchase #2	$179.41	9.317%	$196.1256	$196.13	$196.15	$196.10
Purchase #3	$49.62	4.872%	$52.0375	$52.04	$52.05	$52.00
Purchase #4	$108.81	10.271%	$119.9859	$119.99	$120.00	$120.00
Purchase #5	$135.55	5.194%	$142.5905	$142.59	$142.60	$142.60
Purchase #6	$96.94	6.855%	$103.5852	$103.59	$103.60	$103.60
Purchase #7	$238.63	3.867%	$247.8578	$247.86	$247.85	$247.90
7 purchase totals =	$1,028.72		$1,103.1559	$1,103.17	$1,103.20	$1,103.20