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	$72.31	5.286%	$76.1323	$76.13	$76.15	$76.10
Purchase #2	$150.63	5.299%	$158.6119	$158.61	$158.60	$158.60
Purchase #3	$234.58	5.322%	$247.0643	$247.06	$247.05	$247.10
Purchase #4	$180.44	12.167%	$202.3941	$202.39	$202.40	$202.40
Purchase #5	$126.51	3.579%	$131.0378	$131.04	$131.05	$131.00
Purchase #6	$223.45	4.414%	$233.3131	$233.31	$233.30	$233.30
Purchase #7	$54.81	9.160%	$59.8306	$59.83	$59.85	$59.80
7 purchase totals =	$1,042.73		$1,108.3841	$1,108.37	$1,108.40	$1,108.30