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	$59.58	3.431%	$61.6242	$61.62	$61.60	$61.60
Purchase #2	$72.73	8.562%	$78.9571	$78.96	$78.95	$79.00
Purchase #3	$155.61	9.824%	$170.8971	$170.90	$170.90	$170.90
Purchase #4	$37.64	10.321%	$41.5248	$41.52	$41.50	$41.50
Purchase #5	$229.52	7.862%	$247.5649	$247.56	$247.55	$247.60
Purchase #6	$219.80	3.798%	$228.148	$228.15	$228.15	$228.10
Purchase #7	$231.73	6.743%	$247.3556	$247.36	$247.35	$247.40
7 purchase totals =	$1,006.61		$1,076.0717	$1,076.07	$1,076.00	$1,076.10