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	$185.28	3.816%	$192.3503	$192.35	$192.35	$192.40
Purchase #2	$93.94	11.161%	$104.4246	$104.42	$104.40	$104.40
Purchase #3	$43.29	4.849%	$45.3891	$45.39	$45.40	$45.40
Purchase #4	$41.51	5.243%	$43.6864	$43.69	$43.70	$43.70
Purchase #5	$188.59	6.559%	$200.9596	$200.96	$200.95	$201.00
Purchase #6	$200.33	12.749%	$225.8701	$225.87	$225.85	$225.90
Purchase #7	$187.63	12.760%	$211.5716	$211.57	$211.55	$211.60
7 purchase totals =	$940.57		$1,024.2517	$1,024.25	$1,024.20	$1,024.40