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	$167.25	7.226%	$179.3355	$179.34	$179.35	$179.30
Purchase #2	$198.53	6.748%	$211.9268	$211.93	$211.95	$211.90
Purchase #3	$38.32	5.226%	$40.3226	$40.32	$40.30	$40.30
Purchase #4	$88.89	6.711%	$94.8554	$94.86	$94.85	$94.90
Purchase #5	$144.72	3.827%	$150.2584	$150.26	$150.25	$150.30
Purchase #6	$44.44	12.865%	$50.1572	$50.16	$50.15	$50.20
Purchase #7	$192.64	11.395%	$214.5913	$214.59	$214.60	$214.60
7 purchase totals =	$874.79		$941.4472	$941.46	$941.45	$941.50