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	$156.43	13.826%	$178.058	$178.06	$178.05	$178.10
Purchase #2	$72.26	13.671%	$82.1387	$82.14	$82.15	$82.10
Purchase #3	$87.41	10.552%	$96.6335	$96.63	$96.65	$96.60
Purchase #4	$80.90	10.871%	$89.6946	$89.69	$89.70	$89.70
Purchase #5	$154.27	5.235%	$162.346	$162.35	$162.35	$162.30
Purchase #6	$194.96	8.635%	$211.7948	$211.79	$211.80	$211.80
Purchase #7	$225.55	6.512%	$240.2378	$240.24	$240.25	$240.20
7 purchase totals =	$971.78		$1,060.9034	$1,060.90	$1,060.95	$1,060.80