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	$88.41	9.208%	$96.5508	$96.55	$96.55	$96.60
Purchase #2	$173.57	8.724%	$188.7122	$188.71	$188.70	$188.70
Purchase #3	$113.86	12.171%	$127.7179	$127.72	$127.70	$127.70
Purchase #4	$34.47	3.809%	$35.783	$35.78	$35.80	$35.80
Purchase #5	$186.93	11.686%	$208.7746	$208.77	$208.75	$208.80
Purchase #6	$36.63	11.208%	$40.7355	$40.74	$40.75	$40.70
Purchase #7	$33.59	7.243%	$36.0229	$36.02	$36.00	$36.00
7 purchase totals =	$667.46		$734.2969	$734.29	$734.25	$734.30