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	$160.50	7.558%	$172.6306	$172.63	$172.65	$172.60
Purchase #2	$131.53	3.736%	$136.444	$136.44	$136.45	$136.40
Purchase #3	$149.60	3.270%	$154.4919	$154.49	$154.50	$154.50
Purchase #4	$91.65	7.493%	$98.5173	$98.52	$98.50	$98.50
Purchase #5	$155.59	7.756%	$167.6576	$167.66	$167.65	$167.70
Purchase #6	$205.95	7.653%	$221.7114	$221.71	$221.70	$221.70
Purchase #7	$199.69	11.237%	$222.1292	$222.13	$222.15	$222.10
7 purchase totals =	$1,094.51		$1,173.5820	$1,173.58	$1,173.60	$1,173.50