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	$40.28	9.132%	$43.9584	$43.96	$43.95	$44.00
Purchase #2	$145.32	6.260%	$154.417	$154.42	$154.40	$154.40
Purchase #3	$86.55	3.133%	$89.2616	$89.26	$89.25	$89.30
Purchase #4	$205.37	3.557%	$212.675	$212.68	$212.70	$212.70
Purchase #5	$168.91	5.550%	$178.2845	$178.28	$178.30	$178.30
Purchase #6	$173.45	9.272%	$189.5323	$189.53	$189.55	$189.50
Purchase #7	$148.35	10.625%	$164.1122	$164.11	$164.10	$164.10
7 purchase totals =	$968.23		$1,032.2410	$1,032.24	$1,032.25	$1,032.30