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	$92.30	3.633%	$95.6533	$95.65	$95.65	$95.70
Purchase #2	$42.28	7.443%	$45.4269	$45.43	$45.45	$45.40
Purchase #3	$83.32	6.116%	$88.4159	$88.42	$88.40	$88.40
Purchase #4	$126.33	4.447%	$131.9479	$131.95	$131.95	$131.90
Purchase #5	$28.93	6.861%	$30.9149	$30.91	$30.90	$30.90
Purchase #6	$151.89	11.639%	$169.5685	$169.57	$169.55	$169.60
Purchase #7	$181.96	10.271%	$200.6491	$200.65	$200.65	$200.60
7 purchase totals =	$707.01		$762.5765	$762.58	$762.55	$762.50