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	$194.43	12.212%	$218.1738	$218.17	$218.15	$218.20
Purchase #2	$228.69	4.144%	$238.1669	$238.17	$238.15	$238.20
Purchase #3	$192.51	5.664%	$203.4138	$203.41	$203.40	$203.40
Purchase #4	$27.31	4.495%	$28.5376	$28.54	$28.55	$28.50
Purchase #5	$30.31	8.626%	$32.9245	$32.92	$32.90	$32.90
Purchase #6	$204.37	5.514%	$215.639	$215.64	$215.65	$215.60
Purchase #7	$147.45	7.857%	$159.0351	$159.04	$159.05	$159.00
7 purchase totals =	$1,025.07		$1,095.8907	$1,095.89	$1,095.85	$1,095.80