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	$87.73	7.572%	$94.3729	$94.37	$94.35	$94.40
Purchase #2	$211.42	10.334%	$233.2681	$233.27	$233.25	$233.30
Purchase #3	$122.33	4.160%	$127.4189	$127.42	$127.40	$127.40
Purchase #4	$179.36	13.438%	$203.4624	$203.46	$203.45	$203.50
Purchase #5	$152.43	11.847%	$170.4884	$170.49	$170.50	$170.50
Purchase #6	$139.48	9.242%	$152.3707	$152.37	$152.35	$152.40
Purchase #7	$126.57	4.427%	$132.1733	$132.17	$132.15	$132.20
7 purchase totals =	$1,019.32		$1,113.5547	$1,113.55	$1,113.45	$1,113.70