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	$58.67	3.868%	$60.9394	$60.94	$60.95	$60.90
Purchase #2	$240.50	5.822%	$254.5019	$254.50	$254.50	$254.50
Purchase #3	$69.56	4.779%	$72.8843	$72.88	$72.90	$72.90
Purchase #4	$49.55	4.785%	$51.921	$51.92	$51.90	$51.90
Purchase #5	$118.54	9.818%	$130.1783	$130.18	$130.20	$130.20
Purchase #6	$225.26	5.796%	$238.3161	$238.32	$238.30	$238.30
Purchase #7	$48.32	6.330%	$51.3787	$51.38	$51.40	$51.40
7 purchase totals =	$810.40		$860.1197	$860.12	$860.15	$860.10