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	$197.56	3.801%	$205.0693	$205.07	$205.05	$205.10
Purchase #2	$86.66	3.674%	$89.8439	$89.84	$89.85	$89.80
Purchase #3	$240.80	9.493%	$263.6591	$263.66	$263.65	$263.70
Purchase #4	$72.60	10.850%	$80.4771	$80.48	$80.50	$80.50
Purchase #5	$133.32	12.566%	$150.073	$150.07	$150.05	$150.10
Purchase #6	$39.44	9.854%	$43.3264	$43.33	$43.35	$43.30
Purchase #7	$199.68	7.689%	$215.0334	$215.03	$215.05	$215.00
7 purchase totals =	$970.06		$1,047.4822	$1,047.48	$1,047.50	$1,047.50