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	$62.67	13.180%	$70.9299	$70.93	$70.95	$70.90
Purchase #2	$127.68	7.185%	$136.8538	$136.85	$136.85	$136.90
Purchase #3	$167.25	5.765%	$176.892	$176.89	$176.90	$176.90
Purchase #4	$130.71	12.855%	$147.5128	$147.51	$147.50	$147.50
Purchase #5	$239.43	8.271%	$259.2333	$259.23	$259.25	$259.20
Purchase #6	$85.66	6.693%	$91.3932	$91.39	$91.40	$91.40
Purchase #7	$113.52	5.218%	$119.4435	$119.44	$119.45	$119.40
7 purchase totals =	$926.92		$1,002.2585	$1,002.24	$1,002.30	$1,002.20