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	$216.95	3.683%	$224.9403	$224.94	$224.95	$224.90
Purchase #2	$162.75	6.607%	$173.5029	$173.50	$173.50	$173.50
Purchase #3	$106.74	11.625%	$119.1485	$119.15	$119.15	$119.10
Purchase #4	$76.30	8.318%	$82.6466	$82.65	$82.65	$82.60
Purchase #5	$225.97	7.640%	$243.2341	$243.23	$243.25	$243.20
Purchase #6	$198.78	4.871%	$208.4626	$208.46	$208.45	$208.50
Purchase #7	$54.72	9.414%	$59.8713	$59.87	$59.85	$59.90
7 purchase totals =	$1,042.21		$1,111.8063	$1,111.80	$1,111.80	$1,111.70