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	$144.92	5.461%	$152.8341	$152.83	$152.85	$152.80
Purchase #2	$70.84	3.816%	$73.5433	$73.54	$73.55	$73.50
Purchase #3	$90.90	3.852%	$94.4015	$94.40	$94.40	$94.40
Purchase #4	$136.72	4.514%	$142.8915	$142.89	$142.90	$142.90
Purchase #5	$62.96	10.270%	$69.426	$69.43	$69.45	$69.40
Purchase #6	$235.35	11.727%	$262.9495	$262.95	$262.95	$262.90
Purchase #7	$100.43	11.317%	$111.7957	$111.80	$111.80	$111.80
7 purchase totals =	$842.12		$907.8416	$907.84	$907.90	$907.70