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	$93.83	3.804%	$97.3993	$97.40	$97.40	$97.40
Purchase #2	$187.48	4.745%	$196.3759	$196.38	$196.40	$196.40
Purchase #3	$139.39	7.145%	$149.3494	$149.35	$149.35	$149.30
Purchase #4	$45.41	9.723%	$49.8252	$49.83	$49.85	$49.80
Purchase #5	$148.44	13.731%	$168.8223	$168.82	$168.80	$168.80
Purchase #6	$104.50	6.264%	$111.0459	$111.05	$111.05	$111.00
Purchase #7	$238.29	9.208%	$260.2317	$260.23	$260.25	$260.20
7 purchase totals =	$957.34		$1,033.0497	$1,033.06	$1,033.10	$1,032.90