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	$114.92	7.650%	$123.7114	$123.71	$123.70	$123.70
Purchase #2	$164.84	8.426%	$178.7294	$178.73	$178.75	$178.70
Purchase #3	$166.88	11.603%	$186.2431	$186.24	$186.25	$186.20
Purchase #4	$157.45	6.681%	$167.9692	$167.97	$167.95	$168.00
Purchase #5	$160.33	7.323%	$172.071	$172.07	$172.05	$172.10
Purchase #6	$111.60	5.628%	$117.8808	$117.88	$117.90	$117.90
Purchase #7	$96.78	5.251%	$101.8619	$101.86	$101.85	$101.90
7 purchase totals =	$972.80		$1,048.4668	$1,048.46	$1,048.45	$1,048.50