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	$189.65	3.541%	$196.3655	$196.37	$196.35	$196.40
Purchase #2	$226.55	12.661%	$255.2335	$255.23	$255.25	$255.20
Purchase #3	$189.69	6.410%	$201.8491	$201.85	$201.85	$201.80
Purchase #4	$133.73	3.373%	$138.2407	$138.24	$138.25	$138.20
Purchase #5	$51.52	4.764%	$53.9744	$53.97	$53.95	$54.00
Purchase #6	$128.59	10.318%	$141.8579	$141.86	$141.85	$141.90
Purchase #7	$61.56	5.662%	$65.0455	$65.05	$65.05	$65.00
7 purchase totals =	$981.29		$1,052.5666	$1,052.57	$1,052.55	$1,052.50