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	$166.72	8.760%	$181.3247	$181.32	$181.30	$181.30
Purchase #2	$80.32	13.152%	$90.8837	$90.88	$90.90	$90.90
Purchase #3	$84.71	11.792%	$94.699	$94.70	$94.70	$94.70
Purchase #4	$19.29	5.285%	$20.3095	$20.31	$20.30	$20.30
Purchase #5	$218.86	5.211%	$230.2648	$230.26	$230.25	$230.30
Purchase #6	$58.91	6.788%	$62.9088	$62.91	$62.90	$62.90
Purchase #7	$42.96	5.650%	$45.3872	$45.39	$45.40	$45.40
7 purchase totals =	$671.77		$725.7777	$725.77	$725.75	$725.80