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	$166.41	11.555%	$185.6387	$185.64	$185.65	$185.60
Purchase #2	$12.26	7.579%	$13.1892	$13.19	$13.20	$13.20
Purchase #3	$94.43	5.598%	$99.7162	$99.72	$99.70	$99.70
Purchase #4	$238.37	10.375%	$263.1009	$263.10	$263.10	$263.10
Purchase #5	$209.55	6.560%	$223.2965	$223.30	$223.30	$223.30
Purchase #6	$149.69	4.608%	$156.5877	$156.59	$156.60	$156.60
Purchase #7	$94.59	10.706%	$104.7168	$104.72	$104.70	$104.70
7 purchase totals =	$965.30		$1,046.2460	$1,046.26	$1,046.25	$1,046.20