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	$119.65	6.259%	$127.1389	$127.14	$127.15	$127.10
Purchase #2	$13.86	12.671%	$15.6162	$15.62	$15.60	$15.60
Purchase #3	$159.56	9.465%	$174.6624	$174.66	$174.65	$174.70
Purchase #4	$123.37	6.561%	$131.4643	$131.46	$131.45	$131.50
Purchase #5	$81.44	3.312%	$84.1373	$84.14	$84.15	$84.10
Purchase #6	$94.79	3.802%	$98.3939	$98.39	$98.40	$98.40
Purchase #7	$92.70	7.624%	$99.7674	$99.77	$99.75	$99.80
7 purchase totals =	$685.37		$731.1804	$731.18	$731.15	$731.20