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	$56.53	9.814%	$62.0779	$62.08	$62.10	$62.10
Purchase #2	$49.49	3.730%	$51.336	$51.34	$51.35	$51.30
Purchase #3	$207.30	11.567%	$231.2784	$231.28	$231.30	$231.30
Purchase #4	$179.68	13.761%	$204.4058	$204.41	$204.40	$204.40
Purchase #5	$204.88	3.533%	$212.1184	$212.12	$212.10	$212.10
Purchase #6	$49.56	9.162%	$54.1007	$54.10	$54.10	$54.10
Purchase #7	$191.59	4.850%	$200.8821	$200.88	$200.90	$200.90
7 purchase totals =	$939.03		$1,016.1993	$1,016.21	$1,016.25	$1,016.20