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	$190.63	3.114%	$196.5662	$196.57	$196.55	$196.60
Purchase #2	$98.83	5.481%	$104.2469	$104.25	$104.25	$104.20
Purchase #3	$59.54	5.757%	$62.9677	$62.97	$62.95	$63.00
Purchase #4	$171.77	6.339%	$182.6585	$182.66	$182.65	$182.70
Purchase #5	$92.33	12.416%	$103.7937	$103.79	$103.80	$103.80
Purchase #6	$202.52	9.552%	$221.8647	$221.86	$221.85	$221.90
Purchase #7	$116.52	11.190%	$129.5586	$129.56	$129.55	$129.60
7 purchase totals =	$932.14		$1,001.6563	$1,001.66	$1,001.60	$1,001.80