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	$211.48	5.316%	$222.7223	$222.72	$222.70	$222.70
Purchase #2	$54.86	13.524%	$62.2793	$62.28	$62.30	$62.30
Purchase #3	$65.41	13.739%	$74.3967	$74.40	$74.40	$74.40
Purchase #4	$118.56	7.409%	$127.3441	$127.34	$127.35	$127.30
Purchase #5	$123.78	4.870%	$129.8081	$129.81	$129.80	$129.80
Purchase #6	$103.82	9.123%	$113.2915	$113.29	$113.30	$113.30
Purchase #7	$194.78	3.181%	$200.976	$200.98	$201.00	$201.00
7 purchase totals =	$872.69		$930.8180	$930.82	$930.85	$930.80