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	$225.80	3.306%	$233.2649	$233.26	$233.25	$233.30
Purchase #2	$110.33	10.726%	$122.164	$122.16	$122.15	$122.20
Purchase #3	$224.83	3.488%	$232.6721	$232.67	$232.65	$232.70
Purchase #4	$103.87	7.624%	$111.789	$111.79	$111.80	$111.80
Purchase #5	$32.95	13.116%	$37.2717	$37.27	$37.25	$37.30
Purchase #6	$137.82	3.460%	$142.5886	$142.59	$142.60	$142.60
Purchase #7	$206.53	11.652%	$230.5949	$230.59	$230.60	$230.60
7 purchase totals =	$1,042.13		$1,110.3452	$1,110.33	$1,110.30	$1,110.50