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	$187.87	9.133%	$205.0282	$205.03	$205.05	$205.00
Purchase #2	$91.91	8.130%	$99.3823	$99.38	$99.40	$99.40
Purchase #3	$97.66	8.670%	$106.1271	$106.13	$106.15	$106.10
Purchase #4	$243.26	6.810%	$259.826	$259.83	$259.85	$259.80
Purchase #5	$57.81	4.725%	$60.5415	$60.54	$60.55	$60.50
Purchase #6	$246.86	6.698%	$263.3947	$263.39	$263.40	$263.40
Purchase #7	$98.70	10.507%	$109.0704	$109.07	$109.05	$109.10
7 purchase totals =	$1,024.07		$1,103.3702	$1,103.37	$1,103.45	$1,103.30