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	$176.25	11.515%	$196.5452	$196.55	$196.55	$196.50
Purchase #2	$231.40	13.592%	$262.8519	$262.85	$262.85	$262.90
Purchase #3	$188.88	13.468%	$214.3184	$214.32	$214.30	$214.30
Purchase #4	$75.72	7.113%	$81.106	$81.11	$81.10	$81.10
Purchase #5	$89.81	8.351%	$97.31	$97.31	$97.30	$97.30
Purchase #6	$123.68	13.771%	$140.712	$140.71	$140.70	$140.70
Purchase #7	$82.93	11.287%	$92.2903	$92.29	$92.30	$92.30
7 purchase totals =	$968.67		$1,085.1338	$1,085.14	$1,085.10	$1,085.10