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	$194.78	13.263%	$220.6137	$220.61	$220.60	$220.60
Purchase #2	$113.97	3.521%	$117.9829	$117.98	$118.00	$118.00
Purchase #3	$148.27	9.860%	$162.8894	$162.89	$162.90	$162.90
Purchase #4	$67.46	7.196%	$72.3144	$72.31	$72.30	$72.30
Purchase #5	$52.90	4.537%	$55.3001	$55.30	$55.30	$55.30
Purchase #6	$144.66	4.621%	$151.3447	$151.34	$151.35	$151.30
Purchase #7	$219.88	11.191%	$244.4868	$244.49	$244.50	$244.50
7 purchase totals =	$941.92		$1,024.9320	$1,024.92	$1,024.95	$1,024.90