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	$55.63	13.131%	$62.9348	$62.93	$62.95	$62.90
Purchase #2	$94.56	6.122%	$100.349	$100.35	$100.35	$100.30
Purchase #3	$200.91	4.336%	$209.6215	$209.62	$209.60	$209.60
Purchase #4	$124.78	12.841%	$140.803	$140.80	$140.80	$140.80
Purchase #5	$41.40	9.279%	$45.2415	$45.24	$45.25	$45.20
Purchase #6	$46.84	8.625%	$50.88	$50.88	$50.90	$50.90
Purchase #7	$98.25	3.717%	$101.902	$101.90	$101.90	$101.90
7 purchase totals =	$662.37		$711.7318	$711.72	$711.75	$711.60