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	$153.65	11.588%	$171.455	$171.46	$171.45	$171.50
Purchase #2	$165.27	3.602%	$171.223	$171.22	$171.20	$171.20
Purchase #3	$150.38	7.658%	$161.8961	$161.90	$161.90	$161.90
Purchase #4	$233.86	4.410%	$244.1732	$244.17	$244.15	$244.20
Purchase #5	$173.27	9.117%	$189.067	$189.07	$189.05	$189.10
Purchase #6	$93.28	7.839%	$100.5922	$100.59	$100.60	$100.60
Purchase #7	$160.96	5.820%	$170.3279	$170.33	$170.35	$170.30
7 purchase totals =	$1,130.67		$1,208.7344	$1,208.74	$1,208.70	$1,208.80