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	$128.29	3.162%	$132.3465	$132.35	$132.35	$132.30
Purchase #2	$165.72	3.524%	$171.56	$171.56	$171.55	$171.60
Purchase #3	$206.35	5.310%	$217.3072	$217.31	$217.30	$217.30
Purchase #4	$202.55	6.563%	$215.8434	$215.84	$215.85	$215.80
Purchase #5	$94.63	6.566%	$100.8434	$100.84	$100.85	$100.80
Purchase #6	$82.98	4.636%	$86.827	$86.83	$86.85	$86.80
Purchase #7	$184.61	11.204%	$205.2937	$205.29	$205.30	$205.30
7 purchase totals =	$1,065.13		$1,130.0212	$1,130.02	$1,130.05	$1,129.90