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	$189.79	3.345%	$196.1385	$196.14	$196.15	$196.10
Purchase #2	$241.67	4.227%	$251.8854	$251.89	$251.90	$251.90
Purchase #3	$137.93	4.326%	$143.8969	$143.90	$143.90	$143.90
Purchase #4	$27.60	5.480%	$29.1125	$29.11	$29.10	$29.10
Purchase #5	$107.28	4.169%	$111.7525	$111.75	$111.75	$111.80
Purchase #6	$98.78	4.323%	$103.0503	$103.05	$103.05	$103.10
Purchase #7	$245.47	5.233%	$258.3154	$258.32	$258.30	$258.30
7 purchase totals =	$1,048.52		$1,094.1515	$1,094.16	$1,094.15	$1,094.20