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	$91.89	4.611%	$96.127	$96.13	$96.15	$96.10
Purchase #2	$45.29	12.597%	$50.9952	$51.00	$51.00	$51.00
Purchase #3	$62.59	4.746%	$65.5605	$65.56	$65.55	$65.60
Purchase #4	$213.71	6.739%	$228.1119	$228.11	$228.10	$228.10
Purchase #5	$135.48	12.114%	$151.892	$151.89	$151.90	$151.90
Purchase #6	$31.55	5.243%	$33.2042	$33.20	$33.20	$33.20
Purchase #7	$113.28	4.515%	$118.3946	$118.39	$118.40	$118.40
7 purchase totals =	$693.79		$744.2854	$744.28	$744.30	$744.30