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	$41.73	12.310%	$46.867	$46.87	$46.85	$46.90
Purchase #2	$104.50	4.744%	$109.4575	$109.46	$109.45	$109.50
Purchase #3	$61.85	9.350%	$67.633	$67.63	$67.65	$67.60
Purchase #4	$7.88	9.480%	$8.627	$8.63	$8.65	$8.60
Purchase #5	$76.82	7.764%	$82.7843	$82.78	$82.80	$82.80
Purchase #6	$28.36	6.358%	$30.1631	$30.16	$30.15	$30.20
Purchase #7	$12.45	4.511%	$13.0116	$13.01	$13.00	$13.00
7 purchase totals =	$333.59		$358.5435	$358.54	$358.55	$358.60