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	$108.76	7.550%	$116.9714	$116.97	$116.95	$117.00
Purchase #2	$240.93	7.730%	$259.5539	$259.55	$259.55	$259.60
Purchase #3	$244.31	3.651%	$253.2298	$253.23	$253.25	$253.20
Purchase #4	$236.85	5.822%	$250.6394	$250.64	$250.65	$250.60
Purchase #5	$107.31	10.511%	$118.5894	$118.59	$118.60	$118.60
Purchase #6	$127.69	10.783%	$141.4588	$141.46	$141.45	$141.50
Purchase #7	$201.97	10.191%	$222.5528	$222.55	$222.55	$222.60
7 purchase totals =	$1,267.82		$1,362.9955	$1,362.99	$1,363.00	$1,363.10