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	$133.85	9.873%	$147.065	$147.07	$147.05	$147.10
Purchase #2	$203.56	4.367%	$212.4495	$212.45	$212.45	$212.40
Purchase #3	$176.76	5.623%	$186.6992	$186.70	$186.70	$186.70
Purchase #4	$119.89	6.112%	$127.2177	$127.22	$127.20	$127.20
Purchase #5	$73.90	6.606%	$78.7818	$78.78	$78.80	$78.80
Purchase #6	$130.93	10.565%	$144.7628	$144.76	$144.75	$144.80
Purchase #7	$45.30	7.845%	$48.8538	$48.85	$48.85	$48.90
7 purchase totals =	$884.19		$945.8298	$945.83	$945.80	$945.90