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	$80.85	13.751%	$91.9677	$91.97	$91.95	$92.00
Purchase #2	$7.74	13.220%	$8.7632	$8.76	$8.75	$8.80
Purchase #3	$65.86	8.237%	$71.2849	$71.28	$71.30	$71.30
Purchase #4	$61.95	9.342%	$67.7374	$67.74	$67.75	$67.70
Purchase #5	$99.30	9.815%	$109.0463	$109.05	$109.05	$109.00
Purchase #6	$50.30	12.390%	$56.5322	$56.53	$56.55	$56.50
Purchase #7	$85.65	6.312%	$91.0562	$91.06	$91.05	$91.10
7 purchase totals =	$451.65		$496.3879	$496.39	$496.40	$496.40