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	$186.57	5.244%	$196.3537	$196.35	$196.35	$196.40
Purchase #2	$68.69	6.539%	$73.1816	$73.18	$73.20	$73.20
Purchase #3	$228.41	6.386%	$242.9963	$243.00	$243.00	$243.00
Purchase #4	$107.71	9.832%	$118.3	$118.30	$118.30	$118.30
Purchase #5	$181.34	8.330%	$196.4456	$196.45	$196.45	$196.40
Purchase #6	$16.99	3.861%	$17.646	$17.65	$17.65	$17.60
Purchase #7	$165.39	4.445%	$172.7416	$172.74	$172.75	$172.70
7 purchase totals =	$955.10		$1,017.6648	$1,017.67	$1,017.70	$1,017.60