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	$188.91	3.503%	$195.5275	$195.53	$195.55	$195.50
Purchase #2	$32.56	6.351%	$34.6279	$34.63	$34.65	$34.60
Purchase #3	$228.88	9.451%	$250.5114	$250.51	$250.50	$250.50
Purchase #4	$158.84	7.292%	$170.4226	$170.42	$170.40	$170.40
Purchase #5	$86.50	9.368%	$94.6033	$94.60	$94.60	$94.60
Purchase #6	$133.95	12.795%	$151.0889	$151.09	$151.10	$151.10
Purchase #7	$112.43	13.700%	$127.8329	$127.83	$127.85	$127.80
7 purchase totals =	$942.07		$1,024.6145	$1,024.61	$1,024.65	$1,024.50