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	$217.88	7.840%	$234.9618	$234.96	$234.95	$235.00
Purchase #2	$144.36	7.657%	$155.4136	$155.41	$155.40	$155.40
Purchase #3	$214.60	4.301%	$223.8299	$223.83	$223.85	$223.80
Purchase #4	$35.85	4.632%	$37.5106	$37.51	$37.50	$37.50
Purchase #5	$153.95	8.511%	$167.0527	$167.05	$167.05	$167.10
Purchase #6	$192.62	8.722%	$209.4203	$209.42	$209.40	$209.40
Purchase #7	$97.31	6.687%	$103.8171	$103.82	$103.80	$103.80
7 purchase totals =	$1,056.57		$1,132.0060	$1,132.00	$1,131.95	$1,132.00