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	$194.41	11.379%	$216.5319	$216.53	$216.55	$216.50
Purchase #2	$119.65	9.295%	$130.7715	$130.77	$130.75	$130.80
Purchase #3	$94.53	12.674%	$106.5107	$106.51	$106.50	$106.50
Purchase #4	$16.42	12.707%	$18.5065	$18.51	$18.50	$18.50
Purchase #5	$157.55	6.803%	$168.2681	$168.27	$168.25	$168.30
Purchase #6	$189.60	7.354%	$203.5432	$203.54	$203.55	$203.50
Purchase #7	$166.76	3.123%	$171.9679	$171.97	$171.95	$172.00
7 purchase totals =	$938.92		$1,016.0998	$1,016.10	$1,016.05	$1,016.10