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	$207.42	13.317%	$235.0421	$235.04	$235.05	$235.00
Purchase #2	$155.43	4.619%	$162.6093	$162.61	$162.60	$162.60
Purchase #3	$74.94	4.811%	$78.5454	$78.55	$78.55	$78.50
Purchase #4	$166.36	5.709%	$175.8575	$175.86	$175.85	$175.90
Purchase #5	$73.90	12.159%	$82.8855	$82.89	$82.90	$82.90
Purchase #6	$204.69	3.497%	$211.848	$211.85	$211.85	$211.80
Purchase #7	$115.89	10.617%	$128.194	$128.19	$128.20	$128.20
7 purchase totals =	$998.63		$1,074.9818	$1,074.99	$1,075.00	$1,074.90