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	$175.50	4.609%	$183.5888	$183.59	$183.60	$183.60
Purchase #2	$119.86	6.277%	$127.3836	$127.38	$127.40	$127.40
Purchase #3	$43.81	3.791%	$45.4708	$45.47	$45.45	$45.50
Purchase #4	$129.98	5.620%	$137.2849	$137.28	$137.30	$137.30
Purchase #5	$241.26	9.267%	$263.6176	$263.62	$263.60	$263.60
Purchase #6	$210.75	5.601%	$222.5541	$222.55	$222.55	$222.60
Purchase #7	$204.81	3.649%	$212.2835	$212.28	$212.30	$212.30
7 purchase totals =	$1,125.97		$1,192.1833	$1,192.17	$1,192.20	$1,192.30