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	$33.50	6.655%	$35.7294	$35.73	$35.75	$35.70
Purchase #2	$10.59	8.749%	$11.5165	$11.52	$11.50	$11.50
Purchase #3	$179.87	11.321%	$200.2331	$200.23	$200.25	$200.20
Purchase #4	$41.56	10.461%	$45.9076	$45.91	$45.90	$45.90
Purchase #5	$167.90	11.364%	$186.9802	$186.98	$187.00	$187.00
Purchase #6	$196.82	9.137%	$214.8034	$214.80	$214.80	$214.80
Purchase #7	$62.87	13.571%	$71.4021	$71.40	$71.40	$71.40
7 purchase totals =	$693.11		$766.5723	$766.57	$766.60	$766.50