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	$183.97	6.624%	$196.1562	$196.16	$196.15	$196.20
Purchase #2	$33.30	5.283%	$35.0592	$35.06	$35.05	$35.10
Purchase #3	$107.48	5.734%	$113.6429	$113.64	$113.65	$113.60
Purchase #4	$240.34	9.240%	$262.5474	$262.55	$262.55	$262.50
Purchase #5	$141.86	3.118%	$146.2832	$146.28	$146.30	$146.30
Purchase #6	$70.54	4.850%	$73.9612	$73.96	$73.95	$74.00
Purchase #7	$194.63	12.313%	$218.5948	$218.59	$218.60	$218.60
7 purchase totals =	$972.12		$1,046.2449	$1,046.24	$1,046.25	$1,046.30