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	$190.40	5.617%	$201.0948	$201.09	$201.10	$201.10
Purchase #2	$167.65	13.744%	$190.6918	$190.69	$190.70	$190.70
Purchase #3	$50.95	4.832%	$53.4119	$53.41	$53.40	$53.40
Purchase #4	$79.32	12.410%	$89.1636	$89.16	$89.15	$89.20
Purchase #5	$100.79	3.316%	$104.1322	$104.13	$104.15	$104.10
Purchase #6	$161.56	3.389%	$167.0353	$167.04	$167.05	$167.00
Purchase #7	$239.57	10.384%	$264.4469	$264.45	$264.45	$264.40
7 purchase totals =	$990.24		$1,069.9765	$1,069.97	$1,070.00	$1,069.90