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	$55.74	9.400%	$60.9796	$60.98	$61.00	$61.00
Purchase #2	$239.96	6.417%	$255.3582	$255.36	$255.35	$255.40
Purchase #3	$64.54	5.326%	$67.9774	$67.98	$68.00	$68.00
Purchase #4	$124.85	5.204%	$131.3472	$131.35	$131.35	$131.30
Purchase #5	$142.59	13.658%	$162.0649	$162.06	$162.05	$162.10
Purchase #6	$120.41	3.368%	$124.4654	$124.47	$124.45	$124.50
Purchase #7	$238.52	3.689%	$247.319	$247.32	$247.30	$247.30
7 purchase totals =	$986.61		$1,049.5117	$1,049.52	$1,049.50	$1,049.60