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	$100.26	11.540%	$111.83	$111.83	$111.85	$111.80
Purchase #2	$32.25	7.585%	$34.6962	$34.70	$34.70	$34.70
Purchase #3	$175.87	5.843%	$186.1461	$186.15	$186.15	$186.10
Purchase #4	$74.83	5.146%	$78.6808	$78.68	$78.70	$78.70
Purchase #5	$51.91	13.776%	$59.0611	$59.06	$59.05	$59.10
Purchase #6	$44.43	11.165%	$49.3906	$49.39	$49.40	$49.40
Purchase #7	$50.29	11.124%	$55.8843	$55.88	$55.90	$55.90
7 purchase totals =	$529.84		$575.6891	$575.69	$575.75	$575.70