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	$57.72	7.566%	$62.0871	$62.09	$62.10	$62.10
Purchase #2	$62.50	12.468%	$70.2925	$70.29	$70.30	$70.30
Purchase #3	$65.72	10.513%	$72.6291	$72.63	$72.65	$72.60
Purchase #4	$236.51	13.461%	$268.3466	$268.35	$268.35	$268.30
Purchase #5	$104.50	9.424%	$114.3481	$114.35	$114.35	$114.30
Purchase #6	$56.33	8.418%	$61.0719	$61.07	$61.05	$61.10
Purchase #7	$152.41	8.749%	$165.7444	$165.74	$165.75	$165.70
7 purchase totals =	$735.69		$814.5197	$814.52	$814.55	$814.40