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	$57.59	7.402%	$61.8528	$61.85	$61.85	$61.90
Purchase #2	$158.84	13.856%	$180.8489	$180.85	$180.85	$180.80
Purchase #3	$166.30	4.787%	$174.2608	$174.26	$174.25	$174.30
Purchase #4	$85.79	5.220%	$90.2682	$90.27	$90.25	$90.30
Purchase #5	$197.70	13.132%	$223.662	$223.66	$223.65	$223.70
Purchase #6	$205.46	6.775%	$219.3799	$219.38	$219.40	$219.40
Purchase #7	$180.70	6.310%	$192.1022	$192.10	$192.10	$192.10
7 purchase totals =	$1,052.38		$1,142.3748	$1,142.37	$1,142.35	$1,142.50