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	$86.61	6.506%	$92.2448	$92.24	$92.25	$92.20
Purchase #2	$53.55	11.107%	$59.4978	$59.50	$59.50	$59.50
Purchase #3	$31.92	9.620%	$34.9907	$34.99	$35.00	$35.00
Purchase #4	$164.88	13.581%	$187.2724	$187.27	$187.25	$187.30
Purchase #5	$83.85	9.571%	$91.8753	$91.88	$91.90	$91.90
Purchase #6	$32.73	9.831%	$35.9477	$35.95	$35.95	$35.90
Purchase #7	$224.29	3.162%	$231.382	$231.38	$231.40	$231.40
7 purchase totals =	$677.83		$733.2107	$733.21	$733.25	$733.20