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	$125.60	13.258%	$142.252	$142.25	$142.25	$142.30
Purchase #2	$85.54	12.825%	$96.5105	$96.51	$96.50	$96.50
Purchase #3	$240.76	9.270%	$263.0785	$263.08	$263.10	$263.10
Purchase #4	$159.85	5.678%	$168.9263	$168.93	$168.95	$168.90
Purchase #5	$217.46	7.212%	$233.1432	$233.14	$233.15	$233.10
Purchase #6	$238.77	13.353%	$270.653	$270.65	$270.65	$270.70
Purchase #7	$143.73	3.613%	$148.923	$148.92	$148.90	$148.90
7 purchase totals =	$1,211.71		$1,323.4865	$1,323.48	$1,323.50	$1,323.50