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	$120.59	5.111%	$126.7534	$126.75	$126.75	$126.80
Purchase #2	$102.59	8.725%	$111.541	$111.54	$111.55	$111.50
Purchase #3	$101.53	3.570%	$105.1546	$105.15	$105.15	$105.20
Purchase #4	$197.36	4.826%	$206.8846	$206.88	$206.90	$206.90
Purchase #5	$159.26	13.588%	$180.9002	$180.90	$180.90	$180.90
Purchase #6	$87.75	9.388%	$95.988	$95.99	$96.00	$96.00
Purchase #7	$155.91	11.668%	$174.1016	$174.10	$174.10	$174.10
7 purchase totals =	$924.99		$1,001.3234	$1,001.31	$1,001.35	$1,001.40