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	$113.61	10.448%	$125.48	$125.48	$125.50	$125.50
Purchase #2	$162.41	11.826%	$181.6166	$181.62	$181.60	$181.60
Purchase #3	$205.68	8.473%	$223.1073	$223.11	$223.10	$223.10
Purchase #4	$231.46	3.867%	$240.4106	$240.41	$240.40	$240.40
Purchase #5	$35.27	6.149%	$37.4388	$37.44	$37.45	$37.40
Purchase #6	$18.55	8.506%	$20.1279	$20.13	$20.15	$20.10
Purchase #7	$203.91	6.563%	$217.2926	$217.29	$217.30	$217.30
7 purchase totals =	$970.89		$1,045.4738	$1,045.48	$1,045.50	$1,045.40