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	$62.66	4.508%	$65.4847	$65.48	$65.50	$65.50
Purchase #2	$164.86	4.498%	$172.2754	$172.28	$172.30	$172.30
Purchase #3	$206.35	3.108%	$212.7634	$212.76	$212.75	$212.80
Purchase #4	$24.76	11.837%	$27.6908	$27.69	$27.70	$27.70
Purchase #5	$240.43	6.761%	$256.6855	$256.69	$256.70	$256.70
Purchase #6	$170.27	11.551%	$189.9379	$189.94	$189.95	$189.90
Purchase #7	$135.72	12.686%	$152.9374	$152.94	$152.95	$152.90
7 purchase totals =	$1,005.05		$1,077.7751	$1,077.78	$1,077.85	$1,077.80