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	$45.43	3.144%	$46.8583	$46.86	$46.85	$46.90
Purchase #2	$243.73	9.108%	$265.9289	$265.93	$265.95	$265.90
Purchase #3	$52.89	11.827%	$59.1453	$59.15	$59.15	$59.10
Purchase #4	$240.71	5.424%	$253.7661	$253.77	$253.75	$253.80
Purchase #5	$229.76	13.462%	$260.6903	$260.69	$260.70	$260.70
Purchase #6	$6.35	4.541%	$6.6384	$6.64	$6.65	$6.60
Purchase #7	$197.25	11.312%	$219.5629	$219.56	$219.55	$219.60
7 purchase totals =	$1,016.12		$1,112.5902	$1,112.60	$1,112.60	$1,112.60