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	$55.28	10.828%	$61.2657	$61.27	$61.25	$61.30
Purchase #2	$86.91	6.231%	$92.3254	$92.33	$92.35	$92.30
Purchase #3	$60.80	4.583%	$63.5865	$63.59	$63.60	$63.60
Purchase #4	$32.40	3.578%	$33.5593	$33.56	$33.55	$33.60
Purchase #5	$174.88	7.253%	$187.564	$187.56	$187.55	$187.60
Purchase #6	$247.68	9.688%	$271.6752	$271.68	$271.70	$271.70
Purchase #7	$74.91	10.267%	$82.601	$82.60	$82.60	$82.60
7 purchase totals =	$732.86		$792.5771	$792.59	$792.60	$792.70