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	$214.33	11.231%	$238.4014	$238.40	$238.40	$238.40
Purchase #2	$106.36	4.831%	$111.4983	$111.50	$111.50	$111.50
Purchase #3	$28.96	5.856%	$30.6559	$30.66	$30.65	$30.70
Purchase #4	$22.33	13.348%	$25.3106	$25.31	$25.30	$25.30
Purchase #5	$231.72	11.839%	$259.1533	$259.15	$259.15	$259.20
Purchase #6	$172.85	5.458%	$182.2842	$182.28	$182.30	$182.30
Purchase #7	$207.59	5.767%	$219.5617	$219.56	$219.55	$219.60
7 purchase totals =	$984.14		$1,066.8654	$1,066.86	$1,066.85	$1,067.00