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	$35.95	4.832%	$37.6871	$37.69	$37.70	$37.70
Purchase #2	$59.98	3.410%	$62.0253	$62.03	$62.05	$62.00
Purchase #3	$145.64	3.476%	$150.7024	$150.70	$150.70	$150.70
Purchase #4	$179.41	11.780%	$200.5445	$200.54	$200.55	$200.50
Purchase #5	$52.51	9.266%	$57.3756	$57.38	$57.40	$57.40
Purchase #6	$110.31	7.813%	$118.9285	$118.93	$118.95	$118.90
Purchase #7	$76.93	4.160%	$80.1303	$80.13	$80.15	$80.10
7 purchase totals =	$660.73		$707.3937	$707.40	$707.50	$707.30