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	$148.95	3.419%	$154.0426	$154.04	$154.05	$154.00
Purchase #2	$168.44	10.588%	$186.2744	$186.27	$186.25	$186.30
Purchase #3	$94.76	5.266%	$99.7501	$99.75	$99.75	$99.80
Purchase #4	$110.77	11.543%	$123.5562	$123.56	$123.55	$123.60
Purchase #5	$198.65	13.782%	$226.0279	$226.03	$226.05	$226.00
Purchase #6	$37.83	11.475%	$42.171	$42.17	$42.15	$42.20
Purchase #7	$115.26	13.458%	$130.7717	$130.77	$130.75	$130.80
7 purchase totals =	$874.66		$962.5939	$962.59	$962.55	$962.70