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	$101.75	7.818%	$109.7048	$109.70	$109.70	$109.70
Purchase #2	$145.95	10.650%	$161.4937	$161.49	$161.50	$161.50
Purchase #3	$237.80	11.172%	$264.367	$264.37	$264.35	$264.40
Purchase #4	$113.53	11.608%	$126.7086	$126.71	$126.70	$126.70
Purchase #5	$124.55	5.180%	$131.0017	$131.00	$131.00	$131.00
Purchase #6	$243.69	4.789%	$255.3603	$255.36	$255.35	$255.40
Purchase #7	$106.42	4.316%	$111.0131	$111.01	$111.00	$111.00
7 purchase totals =	$1,073.69		$1,159.6492	$1,159.64	$1,159.60	$1,159.70