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	$223.65	4.568%	$233.8663	$233.87	$233.85	$233.90
Purchase #2	$40.50	12.344%	$45.4993	$45.50	$45.50	$45.50
Purchase #3	$40.32	3.589%	$41.7671	$41.77	$41.75	$41.80
Purchase #4	$168.68	4.218%	$175.7949	$175.79	$175.80	$175.80
Purchase #5	$131.68	7.513%	$141.5731	$141.57	$141.55	$141.60
Purchase #6	$57.27	13.624%	$65.0725	$65.07	$65.05	$65.10
Purchase #7	$165.59	4.632%	$173.2601	$173.26	$173.25	$173.30
7 purchase totals =	$827.69		$876.8333	$876.83	$876.75	$877.00