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	$68.77	8.243%	$74.4387	$74.44	$74.45	$74.40
Purchase #2	$223.86	8.449%	$242.7739	$242.77	$242.75	$242.80
Purchase #3	$79.88	8.194%	$86.4254	$86.43	$86.45	$86.40
Purchase #4	$127.81	13.323%	$144.8381	$144.84	$144.85	$144.80
Purchase #5	$208.85	7.496%	$224.5054	$224.51	$224.50	$224.50
Purchase #6	$100.39	13.731%	$114.1746	$114.17	$114.15	$114.20
Purchase #7	$219.32	3.700%	$227.4348	$227.43	$227.45	$227.40
7 purchase totals =	$1,028.88		$1,114.5909	$1,114.59	$1,114.60	$1,114.50