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	$56.36	11.307%	$62.7326	$62.73	$62.75	$62.70
Purchase #2	$112.89	13.321%	$127.9281	$127.93	$127.95	$127.90
Purchase #3	$78.59	5.223%	$82.6948	$82.69	$82.70	$82.70
Purchase #4	$161.61	3.527%	$167.31	$167.31	$167.30	$167.30
Purchase #5	$16.67	3.744%	$17.2941	$17.29	$17.30	$17.30
Purchase #6	$125.88	11.769%	$140.6948	$140.69	$140.70	$140.70
Purchase #7	$110.28	6.582%	$117.5386	$117.54	$117.55	$117.50
7 purchase totals =	$662.28		$716.1930	$716.18	$716.25	$716.10