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	$33.76	4.797%	$35.3795	$35.38	$35.40	$35.40
Purchase #2	$81.26	6.114%	$86.2282	$86.23	$86.25	$86.20
Purchase #3	$205.60	7.160%	$220.321	$220.32	$220.30	$220.30
Purchase #4	$89.78	4.575%	$93.8874	$93.89	$93.90	$93.90
Purchase #5	$56.39	5.498%	$59.4903	$59.49	$59.50	$59.50
Purchase #6	$243.79	7.678%	$262.5082	$262.51	$262.50	$262.50
Purchase #7	$8.89	5.650%	$9.3923	$9.39	$9.40	$9.40
7 purchase totals =	$719.47		$767.2069	$767.21	$767.25	$767.20