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	$181.37	7.853%	$195.613	$195.61	$195.60	$195.60
Purchase #2	$72.54	4.827%	$76.0415	$76.04	$76.05	$76.00
Purchase #3	$66.72	10.226%	$73.5428	$73.54	$73.55	$73.50
Purchase #4	$172.60	10.259%	$190.307	$190.31	$190.30	$190.30
Purchase #5	$230.52	4.869%	$241.744	$241.74	$241.75	$241.70
Purchase #6	$166.90	4.441%	$174.312	$174.31	$174.30	$174.30
Purchase #7	$85.93	3.772%	$89.1713	$89.17	$89.15	$89.20
7 purchase totals =	$976.58		$1,040.7316	$1,040.72	$1,040.70	$1,040.60