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	$161.55	8.323%	$174.9958	$175.00	$175.00	$175.00
Purchase #2	$217.36	11.406%	$242.1521	$242.15	$242.15	$242.20
Purchase #3	$33.52	5.191%	$35.26	$35.26	$35.25	$35.30
Purchase #4	$153.66	11.217%	$170.896	$170.90	$170.90	$170.90
Purchase #5	$62.28	8.228%	$67.4044	$67.40	$67.40	$67.40
Purchase #6	$156.82	10.249%	$172.8925	$172.89	$172.90	$172.90
Purchase #7	$39.47	10.569%	$43.6416	$43.64	$43.65	$43.60
7 purchase totals =	$824.66		$907.2424	$907.24	$907.25	$907.30