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	$86.69	11.229%	$96.4244	$96.42	$96.40	$96.40
Purchase #2	$164.97	10.635%	$182.5146	$182.51	$182.50	$182.50
Purchase #3	$185.39	3.246%	$191.4078	$191.41	$191.40	$191.40
Purchase #4	$18.48	4.400%	$19.2931	$19.29	$19.30	$19.30
Purchase #5	$220.54	6.862%	$235.6735	$235.67	$235.65	$235.70
Purchase #6	$164.38	12.639%	$185.156	$185.16	$185.15	$185.20
Purchase #7	$107.76	4.484%	$112.592	$112.59	$112.60	$112.60
7 purchase totals =	$948.21		$1,023.0614	$1,023.05	$1,023.00	$1,023.10