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	$55.95	10.222%	$61.6692	$61.67	$61.65	$61.70
Purchase #2	$155.98	6.333%	$165.8582	$165.86	$165.85	$165.90
Purchase #3	$61.81	8.557%	$67.0991	$67.10	$67.10	$67.10
Purchase #4	$138.30	10.178%	$152.3762	$152.38	$152.40	$152.40
Purchase #5	$149.88	7.712%	$161.4387	$161.44	$161.45	$161.40
Purchase #6	$195.74	6.828%	$209.1051	$209.11	$209.10	$209.10
Purchase #7	$189.82	3.299%	$196.0822	$196.08	$196.10	$196.10
7 purchase totals =	$947.48		$1,013.6287	$1,013.64	$1,013.65	$1,013.70