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	$226.69	9.545%	$248.3276	$248.33	$248.35	$248.30
Purchase #2	$116.35	9.433%	$127.3253	$127.33	$127.35	$127.30
Purchase #3	$40.31	8.105%	$43.5771	$43.58	$43.60	$43.60
Purchase #4	$142.28	6.507%	$151.5382	$151.54	$151.55	$151.50
Purchase #5	$172.38	9.753%	$189.1922	$189.19	$189.20	$189.20
Purchase #6	$225.42	9.585%	$247.0265	$247.03	$247.05	$247.00
Purchase #7	$177.87	10.416%	$196.3969	$196.40	$196.40	$196.40
7 purchase totals =	$1,101.30		$1,203.3838	$1,203.40	$1,203.50	$1,203.30