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	$181.49	10.161%	$199.9312	$199.93	$199.95	$199.90
Purchase #2	$201.71	10.212%	$222.3086	$222.31	$222.30	$222.30
Purchase #3	$154.34	5.125%	$162.2499	$162.25	$162.25	$162.20
Purchase #4	$200.98	4.492%	$210.008	$210.01	$210.00	$210.00
Purchase #5	$160.34	8.467%	$173.916	$173.92	$173.90	$173.90
Purchase #6	$46.29	13.540%	$52.5577	$52.56	$52.55	$52.60
Purchase #7	$49.30	8.276%	$53.3801	$53.38	$53.40	$53.40
7 purchase totals =	$994.45		$1,074.3515	$1,074.36	$1,074.35	$1,074.30