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	$211.42	4.749%	$221.4603	$221.46	$221.45	$221.50
Purchase #2	$9.44	11.668%	$10.5415	$10.54	$10.55	$10.50
Purchase #3	$37.82	3.399%	$39.1055	$39.11	$39.10	$39.10
Purchase #4	$42.72	11.728%	$47.7302	$47.73	$47.75	$47.70
Purchase #5	$192.98	8.450%	$209.2868	$209.29	$209.30	$209.30
Purchase #6	$220.87	8.196%	$238.9725	$238.97	$238.95	$239.00
Purchase #7	$81.49	9.781%	$89.4605	$89.46	$89.45	$89.50
7 purchase totals =	$796.74		$856.5573	$856.56	$856.55	$856.60