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	$91.77	4.529%	$95.9263	$95.93	$95.95	$95.90
Purchase #2	$109.59	3.238%	$113.1385	$113.14	$113.15	$113.10
Purchase #3	$223.85	5.194%	$235.4768	$235.48	$235.50	$235.50
Purchase #4	$204.81	9.783%	$224.8466	$224.85	$224.85	$224.80
Purchase #5	$169.42	6.446%	$180.3408	$180.34	$180.35	$180.30
Purchase #6	$160.41	6.171%	$170.3089	$170.31	$170.30	$170.30
Purchase #7	$80.49	12.499%	$90.5504	$90.55	$90.55	$90.60
7 purchase totals =	$1,040.34		$1,110.5883	$1,110.60	$1,110.65	$1,110.50