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	$105.32	7.592%	$113.3159	$113.32	$113.30	$113.30
Purchase #2	$59.81	7.808%	$64.48	$64.48	$64.50	$64.50
Purchase #3	$89.79	11.294%	$99.9309	$99.93	$99.95	$99.90
Purchase #4	$95.43	10.423%	$105.3767	$105.38	$105.40	$105.40
Purchase #5	$56.73	4.427%	$59.2414	$59.24	$59.25	$59.20
Purchase #6	$243.26	5.339%	$256.2477	$256.25	$256.25	$256.20
Purchase #7	$35.77	9.621%	$39.2114	$39.21	$39.20	$39.20
7 purchase totals =	$686.11		$737.8040	$737.81	$737.85	$737.70