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	$126.73	7.605%	$136.3678	$136.37	$136.35	$136.40
Purchase #2	$99.39	12.414%	$111.7283	$111.73	$111.75	$111.70
Purchase #3	$28.61	13.636%	$32.5113	$32.51	$32.50	$32.50
Purchase #4	$228.33	4.276%	$238.0934	$238.09	$238.10	$238.10
Purchase #5	$218.62	11.196%	$243.0967	$243.10	$243.10	$243.10
Purchase #6	$196.58	7.469%	$211.2626	$211.26	$211.25	$211.30
Purchase #7	$83.80	12.757%	$94.4904	$94.49	$94.50	$94.50
7 purchase totals =	$982.06		$1,067.5505	$1,067.55	$1,067.55	$1,067.60