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	$197.33	10.728%	$218.4996	$218.50	$218.50	$218.50
Purchase #2	$173.30	13.589%	$196.8497	$196.85	$196.85	$196.80
Purchase #3	$19.78	4.479%	$20.6659	$20.67	$20.65	$20.70
Purchase #4	$223.90	5.627%	$236.4989	$236.50	$236.50	$236.50
Purchase #5	$194.55	9.678%	$213.3785	$213.38	$213.40	$213.40
Purchase #6	$219.45	11.377%	$244.4168	$244.42	$244.40	$244.40
Purchase #7	$208.69	11.253%	$232.1739	$232.17	$232.15	$232.20
7 purchase totals =	$1,237.00		$1,362.4833	$1,362.49	$1,362.45	$1,362.50