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	$102.63	5.673%	$108.4522	$108.45	$108.45	$108.50
Purchase #2	$164.63	5.547%	$173.762	$173.76	$173.75	$173.80
Purchase #3	$73.64	5.465%	$77.6644	$77.66	$77.65	$77.70
Purchase #4	$234.29	4.168%	$244.0552	$244.06	$244.05	$244.10
Purchase #5	$198.85	8.781%	$216.311	$216.31	$216.30	$216.30
Purchase #6	$82.72	9.271%	$90.389	$90.39	$90.40	$90.40
Purchase #7	$144.29	8.435%	$156.4609	$156.46	$156.45	$156.50
7 purchase totals =	$1,001.05		$1,067.0947	$1,067.09	$1,067.05	$1,067.30