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	$60.51	5.586%	$63.8901	$63.89	$63.90	$63.90
Purchase #2	$195.46	13.698%	$222.2341	$222.23	$222.25	$222.20
Purchase #3	$35.73	5.521%	$37.7027	$37.70	$37.70	$37.70
Purchase #4	$249.63	6.405%	$265.6188	$265.62	$265.60	$265.60
Purchase #5	$135.47	12.326%	$152.168	$152.17	$152.15	$152.20
Purchase #6	$210.29	11.111%	$233.6553	$233.66	$233.65	$233.70
Purchase #7	$77.57	7.741%	$83.5747	$83.57	$83.55	$83.60
7 purchase totals =	$964.66		$1,058.8437	$1,058.84	$1,058.80	$1,058.90