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	$188.29	3.645%	$195.1532	$195.15	$195.15	$195.20
Purchase #2	$118.78	10.343%	$131.0654	$131.07	$131.05	$131.10
Purchase #3	$144.50	10.850%	$160.1783	$160.18	$160.20	$160.20
Purchase #4	$125.79	4.798%	$131.8254	$131.83	$131.85	$131.80
Purchase #5	$170.81	6.379%	$181.706	$181.71	$181.70	$181.70
Purchase #6	$236.65	11.113%	$262.9489	$262.95	$262.95	$262.90
Purchase #7	$157.52	3.169%	$162.5118	$162.51	$162.50	$162.50
7 purchase totals =	$1,142.34		$1,225.3890	$1,225.40	$1,225.40	$1,225.40