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	$168.32	13.815%	$191.5734	$191.57	$191.55	$191.60
Purchase #2	$149.28	11.165%	$165.9471	$165.95	$165.95	$165.90
Purchase #3	$37.84	6.639%	$40.3522	$40.35	$40.35	$40.40
Purchase #4	$224.37	8.872%	$244.2761	$244.28	$244.30	$244.30
Purchase #5	$205.75	5.704%	$217.486	$217.49	$217.50	$217.50
Purchase #6	$223.54	4.375%	$233.3199	$233.32	$233.30	$233.30
Purchase #7	$22.76	3.232%	$23.4956	$23.50	$23.50	$23.50
7 purchase totals =	$1,031.86		$1,116.4503	$1,116.46	$1,116.45	$1,116.50