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	$141.60	7.680%	$152.4749	$152.47	$152.45	$152.50
Purchase #2	$127.94	6.631%	$136.4237	$136.42	$136.40	$136.40
Purchase #3	$190.38	8.138%	$205.8731	$205.87	$205.85	$205.90
Purchase #4	$201.60	11.253%	$224.286	$224.29	$224.30	$224.30
Purchase #5	$37.75	4.460%	$39.4337	$39.43	$39.45	$39.40
Purchase #6	$55.60	11.499%	$61.9934	$61.99	$62.00	$62.00
Purchase #7	$247.78	11.148%	$275.4025	$275.40	$275.40	$275.40
7 purchase totals =	$1,002.65		$1,095.8873	$1,095.87	$1,095.85	$1,095.90