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	$167.67	10.310%	$184.9568	$184.96	$184.95	$185.00
Purchase #2	$12.30	7.821%	$13.262	$13.26	$13.25	$13.30
Purchase #3	$141.72	4.577%	$148.2065	$148.21	$148.20	$148.20
Purchase #4	$121.51	5.214%	$127.8455	$127.85	$127.85	$127.80
Purchase #5	$103.57	10.158%	$114.0906	$114.09	$114.10	$114.10
Purchase #6	$42.70	6.567%	$45.5041	$45.50	$45.50	$45.50
Purchase #7	$141.80	4.763%	$148.5539	$148.55	$148.55	$148.60
7 purchase totals =	$731.27		$782.4194	$782.42	$782.40	$782.50