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	$216.71	12.114%	$242.9622	$242.96	$242.95	$243.00
Purchase #2	$222.46	10.540%	$245.9073	$245.91	$245.90	$245.90
Purchase #3	$82.78	4.792%	$86.7468	$86.75	$86.75	$86.70
Purchase #4	$205.60	12.157%	$230.5948	$230.59	$230.60	$230.60
Purchase #5	$243.82	11.442%	$271.7179	$271.72	$271.70	$271.70
Purchase #6	$178.52	10.326%	$196.954	$196.95	$196.95	$197.00
Purchase #7	$118.33	6.588%	$126.1256	$126.13	$126.15	$126.10
7 purchase totals =	$1,268.22		$1,401.0086	$1,401.01	$1,401.00	$1,401.00