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	$195.87	13.105%	$221.5388	$221.54	$221.55	$221.50
Purchase #2	$167.98	12.126%	$188.3493	$188.35	$188.35	$188.30
Purchase #3	$111.50	3.262%	$115.1371	$115.14	$115.15	$115.10
Purchase #4	$82.35	4.827%	$86.325	$86.33	$86.35	$86.30
Purchase #5	$247.83	8.145%	$268.0158	$268.02	$268.00	$268.00
Purchase #6	$57.93	5.797%	$61.2882	$61.29	$61.30	$61.30
Purchase #7	$113.34	12.116%	$127.0723	$127.07	$127.05	$127.10
7 purchase totals =	$976.80		$1,067.7265	$1,067.74	$1,067.75	$1,067.60