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	$90.73	11.327%	$101.007	$101.01	$101.00	$101.00
Purchase #2	$28.95	12.212%	$32.4854	$32.49	$32.50	$32.50
Purchase #3	$196.55	13.541%	$223.1648	$223.16	$223.15	$223.20
Purchase #4	$48.53	3.271%	$50.1174	$50.12	$50.10	$50.10
Purchase #5	$171.77	11.712%	$191.8877	$191.89	$191.90	$191.90
Purchase #6	$34.28	9.726%	$37.6141	$37.61	$37.60	$37.60
Purchase #7	$115.81	5.543%	$122.2293	$122.23	$122.25	$122.20
7 purchase totals =	$686.62		$758.5057	$758.51	$758.50	$758.50