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	$168.31	3.355%	$173.9568	$173.96	$173.95	$174.00
Purchase #2	$43.50	13.737%	$49.4756	$49.48	$49.50	$49.50
Purchase #3	$68.77	12.404%	$77.3002	$77.30	$77.30	$77.30
Purchase #4	$198.71	4.837%	$208.3216	$208.32	$208.30	$208.30
Purchase #5	$95.40	7.846%	$102.8851	$102.89	$102.90	$102.90
Purchase #6	$43.27	7.378%	$46.4625	$46.46	$46.45	$46.50
Purchase #7	$99.37	10.239%	$109.5445	$109.54	$109.55	$109.50
7 purchase totals =	$717.33		$767.9463	$767.95	$767.95	$768.00