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	$212.76	7.563%	$228.851	$228.85	$228.85	$228.90
Purchase #2	$114.69	11.464%	$127.8381	$127.84	$127.85	$127.80
Purchase #3	$176.79	4.627%	$184.9701	$184.97	$184.95	$185.00
Purchase #4	$114.73	12.323%	$128.8682	$128.87	$128.85	$128.90
Purchase #5	$25.91	4.304%	$27.0252	$27.03	$27.05	$27.00
Purchase #6	$173.61	7.206%	$186.1203	$186.12	$186.10	$186.10
Purchase #7	$168.46	7.726%	$181.4752	$181.48	$181.50	$181.50
7 purchase totals =	$986.95		$1,065.1481	$1,065.16	$1,065.15	$1,065.20